Commit: b27002a Update stylesheet to match TTML2 (#265)

Timed Text Markup Language 1 (TTML1) (Third Edition)

W3C Editors' Draft 17 February 2018

This version:
ttml1.html
Latest editor's draft:
https://w3c.github.io/ttml1/spec/ttml1.html
Latest version:
https://www.w3.org/TR/ttml1/
Previous version:
https://www.w3.org/TR/2013/REC-ttml1-20130924/
Editors:
Glenn Adams, Skynav
Pierre-Anthony Lemieux, MovieLabs
Contributing Authors:
Mike Dolan, Invited Expert
Geoff Freed, WGBH National Center for Accessible Media
Sean Hayes, Microsoft
Erik Hodge, RealNetworks
David Kirby, British Broadcasting Corporation (BBC)
Thierry Michel, W3C
Dave Singer, Apple Computer
Andreas Tai, Invited Expert

Please refer to the errata for this document, which may include normative corrections.

See also translations.


Abstract

This document specifies Timed Text Markup Language (TTML), Version 1, also known as TTML1, in terms of a vocabulary and semantics thereof.

The Timed Text Markup Language is a content type that represents timed text media for the purpose of interchange among authoring systems. Timed text is textual information that is intrinsically or extrinsically associated with timing information.

It is intended to be used for the purpose of transcoding or exchanging timed text information among legacy distribution content formats presently in use for subtitling and captioning functions.

In addition to being used for interchange among legacy distribution content formats, TTML Content may be used directly as a distribution format, for example, providing a standard content format to reference from a <track> element in an HTML5 document, or a <text> or <textstream> media element in a [SMIL 2.1] document.

Status of This Document

This document is an editor's copy that has no official standing.

1 Introduction

Unless specified otherwise, this section and its sub-sections are non-normative.

The Timed Text Markup Language (TTML) Version 1, also referred to as TTML1, provides a standardized representation of a particular subset of textual information with which stylistic, layout, and timing semantics are associated by an author or an authoring system for the purpose of interchange and processing.

TTML is expressly designed to meet only a limited set of requirements established by [TTAF1-REQ], and summarized in I Requirements. In particular, only those requirements which service the need of performing interchange with existing, legacy distribution systems are satisfied.

In addition to being used for interchange among legacy distribution content formats, TTML Content may be used directly as a distribution format, providing, for example, a standard content format to reference from a <track> element in an HTML5 document, or a <text> or <textstream> media element in a [SMIL 2.1] document. Certain properties of TTML support streamability of content, as described in L Streaming TTML Content.

Note:

While TTML is not expressly designed for direct (embedded) integration into an HTML or a SMIL document instance, such integration is not precluded.

Note:

In some contexts of use, it may be appropriate to employ animated content to depict sign language representations of the same content as expressed by a Timed Text Document Instance. This use case is not explicitly addressed by TTML mechanisms, but may be addressed by some external multimedia integration technology, such as SMIL.

Note:

In the first edition of this specification, the version number 1.0 was used to refer to this version of TTML. In this second edition, this version number is simplified to 1 as a result of a determination to call the next (future) version 2 instead of 1.1.

Note:

In previous drafts of this specification, TTML was referred to as DFXP (Distribution Format Exchange Profile). This latter term is retained for historical reasons in certain contexts, such as profile names and designators, and the short name ttaf1-dfxp used in older URLs to refer to this specification. Starting in this edition of the first version of TTML, the short name ttml1 will be used, and subsequent versions of TTML are expected to use short names of ttml2, etc., with integer version numbers.

1.1 System Model

Use of TTML is intended to function in a wider context of Timed Text Authoring and Distribution mechanisms that are based upon the system model depicted in Figure 1 – System Model, wherein the Timed Text Markup Language serves as a bidirectional interchange format among a heterogeneous collection of authoring systems, and as a unidirectional interchange format to a heterogeneous collection of distribution formats after undergoing transcoding or compilation to the target distribution formats as required, and where one particular distribution format is TTML (labeled as "DFXP" in the figure).

Figure 1 – System Model
System Model

1.2 Document Example

A TTML Document Instance consists of a tt document element that contains a header and a body, where the header specifies document level metadata, styling definitions and layout definitions, and the body specifies text content intermixed with references to style and layout information and inline styling and timing information.

Example Fragment – TTML Document Structure
<tt xml:lang="" xmlns="http://www.w3.org/ns/ttml">
  <head>
    <metadata/>
    <styling/>
    <layout/>
  </head>
  <body/>
</tt>

Document level metadata may specify a document title, description, and copyright information. In addition, arbitrary metadata drawn from other namespaces may be specified.

Example Fragment – TTML Metadata
<metadata xmlns:ttm="http://www.w3.org/ns/ttml#metadata">
  <ttm:title>Timed Text TTML Example</ttm:title>
  <ttm:copyright>The Authors (c) 2006</ttm:copyright>
</metadata>

Styling information may be specified in the form of style specification definitions that are referenced by layout and content information, specified inline with content information, or both.

In Example Fragment – TTML Styling, four style sets of specifications are defined, with one set serving as a collection of default styles.

Example Fragment – TTML Styling
<styling xmlns:tts="http://www.w3.org/ns/ttml#styling">
  <!-- s1 specifies default color, font, and text alignment -->
  <style xml:id="s1"
    tts:color="white"
    tts:fontFamily="proportionalSansSerif"
    tts:fontSize="22px"
    tts:textAlign="center"
  />
  <!-- alternative using yellow text but otherwise the same as style s1 -->
  <style xml:id="s2" style="s1" tts:color="yellow"/>
  <!-- a style based on s1 but justified to the right -->
  <style xml:id="s1Right" style="s1" tts:textAlign="end" />     
  <!-- a style based on s2 but justified to the left -->
  <style xml:id="s2Left" style="s2" tts:textAlign="start" />
</styling>

Layout information defines one or more regions into which content is intended to be presented. A region definition may reference one or more sets of style specifications in order to permit content flowed in the region to inherit from these styles. In Example Fragment – TTML Layout, the region definition makes reference to style specification s1 augmented by specific inline styles which, together, allow content flowed into the region to inherit from the region's styles (in the case that a style is not already explicitly specified on content or inherited via the content hierarchy.)

Example Fragment – TTML Layout
<layout xmlns:tts="http://www.w3.org/ns/ttml#styling">
  <region xml:id="subtitleArea"
    style="s1"
    tts:extent="560px 62px"
    tts:padding="5px 3px"
    tts:backgroundColor="black"
    tts:displayAlign="after"
  />
</layout>  

The content of a Document Instance is expressed in its body, which is organized in terms of block and inline text elements. The hierarchical organization of content elements serves a primary role in determining both spatial and temporal relationships. For example, in Example Fragment – TTML Body, each paragraph (p element) is flowed into its target region in the specified lexical order; furthermore, the active time interval of each paragraph is timed in accordance to its parent or sibling according to the applicable time containment semantics — in this case, the division parent is interpreted (by default) as a parallel time container.

Example Fragment – TTML Body
<body region="subtitleArea">
  <div>
    <p xml:id="subtitle1" begin="0.76s" end="3.45s">
      It seems a paradox, does it not,
    </p>
    <p xml:id="subtitle2" begin="5.0s" end="10.0s">
      that the image formed on<br/>
      the Retina should be inverted?
    </p>
    <p xml:id="subtitle3" begin="10.0s" end="16.0s" style="s2">
      It is puzzling, why is it<br/>
      we do not see things upside-down?
    </p>
    <p xml:id="subtitle4" begin="17.2s" end="23.0s">
      You have never heard the Theory,<br/>
      then, that the Brain also is inverted?
    </p>
    <p xml:id="subtitle5" begin="23.0s" end="27.0s" style="s2">
      No indeed! What a beautiful fact!
    </p>
    <p xml:id="subtitle6a" begin="28.0s" end="34.6s" style="s2Left">
      But how is it proved?
    </p>
    <p xml:id="subtitle6b" begin="28.0s" end="34.6s" style="s1Right">
      Thus: what we call
    </p>
    <p xml:id="subtitle7" begin="34.6s" end="45.0s" style="s1Right">
      the vertex of the Brain<br/>
      is really its base
    </p>
    <p xml:id="subtitle8" begin="45.0s" end="52.0s" style="s1Right">
      and what we call its base<br/>
      is really its vertex,
    </p>
    <p xml:id="subtitle9a" begin="53.5s" end="58.7s">
      it is simply a question of nomenclature.
    </p>
    <p xml:id="subtitle9b" begin="53.5s" end="58.7s" style="s2">
      How truly delightful!
    </p>
  </div>    
</body>

The first subtitle Subtitle 1 – Time Interval [0.76, 3.45) is presented during the time interval 0.76 to 3.45 seconds. This subtitle inherits its font family, font size, foreground color, and text alignment from the region into which it is presented. Since no region is explicitly specified on the paragraph, the nearest ancestor that specifies a region determines the targeted region. Note also that content is presented at the bottom (after edge) of the containing region due to the tts:displayAlign="after" being specified on the region definition.

Note:

The notation "[X,Y]" denotes a closed interval from X to Y, including X and Y; "[X,Y)" denotes a right half-open interval from X to Y, including X but not including Y; "(X,Y]" denotes a left half-open interval from X to Y, not including X but including Y; "(X,Y)" denotes an open interval from X to Y, not including X or Y.

Note:

In this example, the p element is used as a presentational element rather than as a semantic element, i.e., as a linguistic paragraph. It is up to an author to determine which TTML elements are used to convey the intended meaning. For instance, this example could be written to use timing on span elements in order to preserve the integrity of semantic paragraphs.

Subtitle 1 – Time Interval [0.76, 3.45)
Subtitle 1

The second subtitle continues with the default style, except that it contains two lines of text with an intervening author-specified line break. Note the effects of the use of tts:textAlign="center" to specify the paragraph's alignment in the inline progression direction.

Subtitle 2 – Time Interval [5.0, 10.0)
Subtitle 2

The third subtitle continues, using a variant style which overrides the default style's foreground color with a different color.

Subtitle 3 – Time Interval [10.0, 16.0)
Subtitle 3

The fourth subtitle reverts to the default style.

Subtitle 4 – Time Interval [17.2, 23.0)
Subtitle 4

The fifth subtitle continues, again using a variant style which overrides the default style's foreground color with a different color.

Subtitle 5 – Time Interval [23.0, 27.0)
Subtitle 5

During the next active time interval, two distinct subtitles are simultaneously active, with the paragraphs expressing each subtitle using different styles that override color and paragraph text alignment of the default style. Note that the flow order is determined by the lexical order of elements as they appear in the content hierarchy.

Subtitles 6a and 6b – Time Interval [28.0, 34.6)
Subtitles 6a and 6b

The next subtitle is specified in a similar manner using a style override to give the paragraph right (end) justification in the inline progression direction.

Subtitle 7 – Time Interval [34.6, 45.0)
Subtitles 7a and 7b

The eighth subtitle uses the same style override as the previous subtitle in order to maintain the right (end) justification of the paragraph.

Subtitle 8 – Time Interval [47.3, 49.0)
Subtitle 8

During the final (ninth) active time interval, two distinct subtitles are again simultaneously active, but with a different style applied to the second paragraph to override the default color. Note that the flow order is determined by the lexical order of elements as they appear in the content hierarchy.

Subtitles 9a and 9b – Time Interval [53.5, 58.7)
Subtitles 9a and 9b

The examples shown above demonstrate the primary types of information that may be authored using TTML: metadata, styling, layout, timing, and content. In typical cases, styling and layout information are separately specified in a Document Instance. Content information is expressed in a hierarchical fashion that embodies the organization of both spatial (flow) and timing information. Content makes direct or indirect references to styling and layout information and may specify inline overrides to styling.

2 Definitions

2.1 Acronyms

DFXP

Distribution Format Exchange Profile

TT

Timed Text

TTML

Timed Text Markup Language

TTAF

Timed Text Authoring Format

TTWG

Timed Text Working Group

2.2 Terminology

Abstract Document Instance

An instance of an abstract data set as represented by a Reduced XML Infoset.

Abstract Document Type

A set of constraints that defines a class of XML Information Sets [XML InfoSet].

Attribute Information Item

Each specified or defaulted attribute of an XML document corresponds with an attribute information item as defined by [XML InfoSet], §2.3.

Character Information Item

Each data character appearing in an XML document corresponds with a character information item as defined by [XML InfoSet], §2.6.

Computed Cell Size

The size (extent) of a cell computed by dividing the width of the Root Container Region by the column count, i.e., the number of cells in the horizontal axis, and by dividing the height of the Root Container Region by the row count, i.e., the number of cells in the vertical axis, where the column and row counts are determined by the ttp:cellResolution parameter attribute.

Content Processor

A processing system capable of importing (receiving) Timed Text Markup Language content for the purpose of transforming, presenting, or otherwise processing the content.

Content Region

A logical region into which rendered content is placed when modeling or performing presentation processing.

Document Instance

A concrete realization of a Timed Text Markup Language document, where the concrete form is specific to the context of reference. For example, a sequence of bytes that represents an XML serialization of a Timed Text document, an internal, parsed representation of such a Timed Text document, etc.

Document Interchange Context

The implied context or environment external to a Content Processor in which document interchange occurs, and in which out-of-band protocols or specifications may define certain behavioral defaults, such as an implied profile.

Document Processing Context

The implied context or environment internal to a Content Processor in which document processing occurs, and in which out-of-band protocols or specifications may define certain behavioral defaults, such as the establishment or creation of a Synthetic Document Syncbase.

Element Information Item

Each element appearing in an XML document corresponds with an element information item as defined by [XML InfoSet], §2.2.

Exchange Profile

A profile of content that serves a set of needs for content interchange.

Extension

A syntactic or semantic expression or capability that is defined and labeled (using a extension designation) in another (public or private) specification.

Feature

A syntactic or semantic expression or capability that is defined and labeled (using a feature designation) in this specification (or a future revision of this specification).

Presentation Processor

A Content Processor which purpose is to layout, format, and render, i.e., to present, Timed Text Markup Language content by applying the presentation semantics defined in this specification.

Processor

See Content Processor.

Profile Definition Document

A document that defines a specific collection of features and extensions for which support is required or optional in a recipient content processor.

Region

A logical construct that models authorial intention regarding desired or potential presentation processing, and which is represented as a rectangular area of a presentation surface, i.e., a region area, into which content is composed and rendered during presentation processing.

Reduced XML Infoset

An XML Information Set [XML InfoSet] that satisfies the constraints specify by A Reduced XML Infoset.

Related Media Object

A (possibly null) media object associated with or otherwise related to a Document Instance. For example, an aggregate audio/video media object for which a Document Instance provides caption or subtitle information, and with which that Document Instance is associated.

Related Media Object Region

When a non-null Related Media Object exists, the region of this media object, expressed in the coordinate system that applies to the Document Instance that is associated with the related media object.

Root Container Region

A logical region that establishes a coordinate system into which Document Instance content regions are placed and optionally clipped.

Root Temporal Extent

The temporal extent (interval) defined by the temporal beginning and ending of a Document Instance in relationship with some external application or presentation context.

SMPTE Time Code

A time code whose format and semantics are established by [SMPTE 12M], which may be embedded into or otherwise associated with media content, such as a broadcast audio/video stream.

Synthetic Document Syncbase

A document level syncbase [SMIL 2.1], § 10.7.1, synthesized or otherwise established by the Document Processing Context in accordance with the Related Media Object or other processing criteria.

Synthetic SMPTE Document Syncbase

A Synthetic Document Syncbase constructed from SMPTE Time Code values embedded in or associated with the Related Media Object or otherwise determined by the Document Processing Context.

Timed Text

Textual information that is intrinsically or extrinsically associated with timing information.

Timed Text Markup Language

A content type that represents timed text media for the purpose of interchange among authoring systems.

Timed Text Authoring System

A content authoring system capable of importing and exporting Timed Text Markup Language content.

Transformation Processor

A Content Processor which purpose is to transform or otherwise rewrite Timed Text Markup Language content to either Timed Text Markup Language or to another (arbitrary) content format. An example of the first is a processor that removes or rewrites TTML features so as to conform to a profile of TTML. An example of the latter is a processor that translates TTML into a completely different timed text format. Because this specification does not otherwise define a target profile or format for transformation processing, no further transformation semantics are defined by this specification.

Valid Abstract Document Instance

An Abstract Document Instance which has been assessed for validity and found to be valid as defined by 4 Document Types.

2.3 Documentation Conventions

Within normative prose in this specification, the words may, should, and must are defined as follows:

may

Conforming documents and/or TTML processors are permitted to, but need not behave as described.

should

Conforming documents and/or TTML processors are strongly recommended to, but need not behave as described.

must

Conforming documents and/or TTML processors are required to behave as described; otherwise, they are in error.

If normative specification language takes an imperative form, then it is to be treated as if the term must applies. Furthermore, if normative language takes a declarative form, and this language is governed by must, then it is also to be treated as if the term must applies.

Note:

For example, the phrases "treat X as an error" and "consider X as an error" are to be read as mandatory requirements in the context of use. Similarly, if the specification prose is "X must apply", "X applies", or "X is mandatory", and "X" is further defined as "X is Y and Z", then, by transitive closure, this last declarative phrase is to be read as "Y is mandatory" and "Z is mandatory" in the context of use.

All normative syntactic definitions of XML representations and other related terms are depicted with a light yellow-orange background color and labeled as "XML Representation" or "Syntax Representation", such as in the following:

XML Representation – Element Information Item: example
<example
  count = integer
  size = (large|medium|small) : medium>
  Content: (all | any*)
</example>

In an XML representation, bold-face attribute names (e.g. count above) indicate a required attribute information item, and the rest are optional. Where an attribute information item has an enumerated type definition, the values are shown separated by vertical bars, as for size above; if there is a default value, it is shown following a colon. Where an attribute information item has a built-in simple type definition defined in [XML Schema Part 2], a hyperlink to its definition therein is given.

The allowed content of the information item is shown as a grammar fragment, using the Kleene operators ?, * and +. Each element name therein is a hyperlink to its own illustration.

The term linear white-space (LWSP) is to be interpreted as a non-empty sequence of SPACE (U+0020), TAB (U+0009), CARRIAGE RETURN (U+000D), or LINE FEED (U+000A), which corresponds to production [3] S as defined by [XML 1.0].

All content of this specification that is not explicitly marked as non-normative is considered to be normative. If a section or appendix header contains the expression "Non-Normative", then the entirety of the section or appendix is considered non-normative.

All paragraphs marked as a Note are considered non-normative.

Example code fragments are depicted with a light blue-green background color and labeled as "Example Fragment", such as in the following:

Example Fragment – Sample
<tt xml:lang="" xmlns="http://www.w3.org/ns/ttml">
  <head>
    <metadata/>
    <styling/>
    <layout/>
  </head>
  <body/>
</tt>

3 Conformance

This section specifies the general conformance requirements for TTML Content and processors.

3.1 Content Conformance

A TTML Document Instance conforms to this specification if the following criteria are satisfied:

  1. When transporting a Document Instance in a Document Interchange Context in which a Media Type [Media Types] identifies the content type of the interchanged Document Instance, then the specified media type is application/ttml+xml in conformance with [XML Media Types] § 7, with which an optional profile parameter may appear, the value of which conforms to a profile designator as defined by 5.2 Profiles.

  2. The Document Instance is or can be represented as a Reduced XML Infoset as defined by A Reduced XML Infoset.

  3. The Reduced XML Infoset that corresponds to the Document Instance is or can be associated with one of the Abstract Document Types defined by 4 Document Types.

  4. The Reduced XML Infoset that corresponds to the Document Instance is a Valid Abstract Document Instance of the associated Abstract Document Type.

  5. The Reduced XML Infoset satisfies all additional mandatory syntactic and semantic constraints defined by this specification. In addition, this Infoset should satisfy the web content accessibility guidelines specified by [WCAG].

3.2 Processor Conformance

3.2.1 Generic Processor Conformance

A TTML Content Processor conforms to this specification if the following generic processor criteria are satisfied:

  1. The processor provides at least one mechanism for notionally instantiating a Reduced XML Infoset representation of a conformant Document Instance.

  2. If a process does or can perform validation of a candidate Document Instance, then it provides at least one mechanism to implicitly or explicitly associate the Reduced XML Infoset representation of a conformant Document Instance with one of the Abstract Document Types defined by 4 Document Types.

  3. The processor does not a priori reject or abort the processing of a conformant Document Instance unless the processor does not support some required (mandatory) feature specified or implied by a TTML profile declared to apply to the Document Instance.

  4. The processor supports all mandatory processing semantics defined by this specification.

    Note:

    The phrase mandatory semantics refers to all explicit use of the conformance key phrases must and must not as well as any declarative statement that can be reasonably inferred from such key phrases. For example, these mandatory semantics include support for all features marked as mandatory in D.2 Feature Support.

  5. If the processor supports some optional processing semantics defined by this specification, then it does so in a manner consistent with the defined semantics.

    Note:

    The phrase optional semantics refers to all explicit use of the conformance key phrases should, should not, may, and may not, as well as any declarative statement that can be reasonably inferred from such key phrases. For example, these optional semantics include support for all features marked as optional in D.2 Feature Support.

3.2.2 Transformation Processor Conformance

A TTML Content Processor is a conformant TTML Transformation Processor if the following criteria are satisfied:

  1. The processor satisfies all requirements specified by 3.2.1 Generic Processor Conformance.

  2. The processor supports the DFXP Transformation profile as specified by F.1 DFXP Transformation Profile.

3.2.3 Presentation Processor Conformance

A TTML Content Processor is a conformant TTML Presentation Processor if the following criteria are satisfied:

  1. The processor satisfies all requirements specified by 3.2.1 Generic Processor Conformance.

  2. The processor supports the DFXP Presentation profile as specified by F.2 DFXP Presentation Profile.

3.3 Claims

Any claim of compliance with respect to the conformance of a TTML Document Instance or Content Processor must make reference to an implementation compliance statement (ICS).

An implementation compliance statement must identify all mandatory and optional features of this specification that are satisfied by the document instance or the content processor implementation. In particular, the statement must identify the utilized or supported TTML vocabulary profile(s) as defined by 5.2 Profiles, and, if a subset or superset profile is used or supported, then what features are excluded or included in the subset or superset profile.

A Document Instance for which a compliance claim is made must specify either (1) a ttp:profile attribute on its root tt element as defined by 6.2.8 ttp:profile or (2) a ttp:profile element as a child of the head element as defined by 6.1.1 ttp:profile.

4 Document Types

This section defines the following TTML Abstract Document Types:

Each Abstract Document Type consists of the following constraints:

An Abstract Document Instance may be assessed in terms of validity, and is considered to be a Valid Abstract Document Instance if it satisfies the following condition: if after

  1. pruning all element information items whose names are not members of the collection of element types defined by the associated Abstract Document Type, then

  2. pruning character information item children from any remaining element in case that all character children of the element denote XML whitespace characters and the element's type is defined as empty in the associated Abstract Document Type, and then

  3. pruning all attribute information items having expanded names such that the namespace URI of the expanded names are not listed in Table 1 – Namespaces, or, if listed in Table 1 – Namespaces, are not members of the collection of attributes defined by the associated Abstract Document Type for use with the owning element information item,

then the document element is one of the document element types permitted by the associated Abstract Document Type, the descendants of the document element satisfy their respective element type's content specifications, all required attributes are present, and the declared value of each attribute satisfies the type declared by the associated Abstract Document Type.

Note:

While a conformant processor may not a priori reject a conformant Document Instance, a given Document Instance may be constrained by the author or authoring tool to satisfy a more restrictive definition of validity.

Note:

As illustrated in the following example, an Abstract Document Instance can be a Valid Abstract Document Instance even if it includes elements and attributes whose namespace names are listed in Table 1 – Namespaces but whose local names are not part of the vocabulary defined by this version of the specification. Specifically, the element foo and the attribute tts:foo are pruned by above steps (1) and (3), respectively, because they are not members of the associated Abstract Document Type, even though their namespace names are listed in Table 1 – Namespaces.

Example Fragment – Pruning of elements and attributes that are not members of the associated Abstract Document Type
<tt
  xmlns="http://www.w3.org/ns/ttml"
  xmlns:tts="http://www.w3.org/ns/ttml#styling"
  xml:lang="en">
  <body>
    <foo>Foo</foo>
    <div>
      <p
        tts:foo="bar">
          Bar
      </p>
    </div>
  </body>
</tt>

4.1 TTML Content

TTML Content is an Abstract Document Type of a profile of the Timed Text Markup Language intended to be used for interchange among distribution systems. This document type is defined in terms of the element and attribute vocabulary specified in 5 Vocabulary.

This specification references two types of schemas that may be used to validate a superset/subset of conformant TTML Content Document Instances:

The (root) document element of a TTML Content Document Instance must be a tt element, as defined by 7.1.1 tt.

Note:

The schemas referenced by this specification do not validate all syntactic constraints defined by this specification, and, as such, represent a superset of conformant TTML Content. In particular, performing validation with one of the above referenced schemas may result in a false positive indication of validity. For example, both the RNC and XSD schemas specify that a tts:fontFamily attribute must satisfy the xs:string XSD data type; however, this data type is a superset of the values permitted to be used with the tts:fontFamily attribute.

In addition, the RNC schema may produce a false negative indication of validity when using the xml:id attribute with an element in a foreign namespace, thus representing a subset of conformant TTML Content. This is due to a specific limitation in expressing wildcard patterns involving xsd:ID typed attributes in Relax NG schemas. Note that this specification defines the formal validity of a Document Instance to be based on an Abstract Document Instance from which all foreign namespace elements and attributes have been removed. Therefore, the exceptional reporting of this false negative does not impact the formal assessment of Document Instance validity.

Note:

The schemas referenced by this specification are intended for use after the pruning steps (1)-(3) specified by 4 Document Types have been applied.

5 Vocabulary

This section defines the namespaces, profiles, and vocabulary (as an element and attribute catalog) of the Timed Text Markup Language (TTML) as follows:

5.1 Namespaces

The Timed Text Markup Language (TTML) employs a number of XML Namespaces [XML Namespaces 1.0] for elements and certain global attributes. The following table specifies this set of namespaces and indicates the default prefix used within this specification and the normative URI that denotes each namespace.

Note:

In a specific Document Instance, it is not required that the default prefixes shown below are used. Any prefix or namespace binding that satisfies the constraints of XML Namespaces [XML Namespaces 1.0] may be used that is associated with the specified namespace URI.

Table 1 – Namespaces
NamePrefixValue
TTtt:http://www.w3.org/ns/ttml
TT Parameterttp:http://www.w3.org/ns/ttml#parameter
TT Styletts:http://www.w3.org/ns/ttml#styling
TT Metadatattm:http://www.w3.org/ns/ttml#metadata
TT Profilenonehttp://www.w3.org/ns/ttml/profile/
TT Featurenonehttp://www.w3.org/ns/ttml/feature/
TT Extensionnonehttp://www.w3.org/ns/ttml/extension/

Note:

If a reference to an element type is used in this specification and the name of the element type is not namespace qualified, then the TT Namespace applies.

For certain namespaces defined above, the default prefix is specified as none if no XML vocabulary is defined in the namespace by this specification (nor expected to be defined in a future version of this specification). In such cases, the use of the namespace URI is for purposes other than defining XML vocabulary, e.g., for designating profiles, features, extensions and for dereferencing standard profile definitions.

All TTML Namespaces are mutable [NSState]; all undefined names in these namespaces are reserved for future standardization by the W3C.

5.2 Profiles

The Timed Text Markup Language (TTML) employs a number of standard, predefined profiles of its vocabulary and associated semantics. The following table specifies this set of profiles, indicating a normative name and designator for each predefined profile, and where each of these profiles is formally elaborated in F Profiles or in another TTWG specification.

Table 2 – Profiles
NameDesignator
DFXP Transformationhttp://www.w3.org/ns/ttml/profile/dfxp-transformation
DFXP Presentationhttp://www.w3.org/ns/ttml/profile/dfxp-presentation
DFXP Fullhttp://www.w3.org/ns/ttml/profile/dfxp-full
SDP UShttp://www.w3.org/ns/ttml/profile/sdp-us

A profile designator must adhere to the xsd:anyURI data type defined by [XML Schema Part 2], §3.2.17. If the profile designator is expressed as a relative URI, then it must be absolutized by using the TT Profile Namespace value as the base URI.

Note:

For example, if a profile designator is expressed as dfxp-presentation, then the absolutized profile designator would be http://www.w3.org/ns/ttml/profile/dfxp-presentation.

All profile designators which have the TT Profile Namespace as a prefix but are otherwise not listed in Table 2 – Profiles are reserved for future standardization, and must not be appear in a conformant Document Instance. Nothwithstanding this constraint, a profile designator is not restricted to the set of designators enumerated in Table 2 – Profiles, but may be any URI that feasibly dereferences a TTML Profile Definition Document provided it does not use the TT Profile Namespace as a prefix.

The profile of TTML that must be supported by a TTML Content Processor in order to process a Document Instance is determined either (1) by specifying a ttp:profile attribute on the root tt element, as defined by 6.2.8 ttp:profile, or (2) by including one or more ttp:profile elements in the head element, in accordance with 6.1.1 ttp:profile.

If a ttp:profile element appears as a descendant of the tt element, then the ttp:profile attribute should not be specified on the tt element. If both a ttp:profile element and a ttp:profile attribute are present (in a given Document Instance), then the ttp:profile attribute must be ignored for the purpose of determining the declared profile requirements.

If more than one ttp:profile element appears in a Document Instance, then all specified profiles apply simultaneously. In such a case, if some feature or some extension is specified by one profile to be used (mandatory and enabled) and by another profile to be required (mandatory) or optional (voluntary), then that feature or extension must be considered to be used (mandatory and enabled); if some feature or some extension is specified by one profile to be merely required (mandatory) and by another profile to be optional (voluntary), then that feature or extension must be considered to be required (mandatory).

If neither ttp:profile attribute nor ttp:profile element is present in a Document Instance, and if the Document Interchange Context does not make an implicit or explicit reference to a pre-defined profile or does not specify a Profile Definition Document or another equivalent set of feature designations, then the DFXP Transformation profile applies.

Note:

It is not a requirement on a conformant Document Instance that a profile be internally defined by use of a ttp:profile element or internally referenced by a ttp:profile attribute. More specifically, it is permitted that the Document Interchange Context determines the applicable profile through private agreement, out-of-band protocol, or common use (between sender and receiver) of a profile defined by an external specification.

Note:

It is intended that the ttp:profile attribute be used when the author wishes to reference one of the standard, predefined profiles of TTML Content, and does not wish to modify (by supersetting or subsetting) that profile. This attribute may also be used by an author to indicate the use of a non-standard profile, in which case the specified profile designator expresses a URI that denotes an externally defined Profile Definition Document. However, it is not required that a conformant TTML Content Processor be able to dereference such an externally specified profile definition.

In contrast, it is intended that the ttp:profile element be used when the author wishes to make use of a modified predefined profile or wishes to include in the Document Instance a non-standard profile definition not based upon one of the predefined profiles.

A predefined profile is supersetted by specifying some feature or extension to be required (mandatory) that was either not specified in the underlying, baseline profile or was specified as optional (voluntary) in the baseline profile. A predefined profile is subsetted by specifying some feature or extension to be optional (voluntary) that was specified as required (mandatory) in the underlying, baseline profile.

When a baseline profile is modified by subsetting, the resulting, derived profile is referred to as a subtractive profile; when modified by supersetting, the result is referred to as an additive profile. It is also possible to define a derived profile that is simultaneously subtractive and additive.

If a Document Instance makes use of a feature defined by D.1 Feature Designations and if the intended use of the document requires the recognition and processing of that feature, then the document must include a required feature or a used feature specification in one of its declared or referenced profiles. If a Document Instance makes use of an extension designatable by E.1 Extension Designations and if the intended use of the document requires the recognition and processing of that extension, then the document must include a required extension or a used extension specification in one of its declared or referenced profiles.

Note:

A required feature or used feature specification is expressed directly (or indirectly by referring to a profile) by means of a ttp:feature element where the value of its value attribute is required or use, respectively. A required extension or used extension specification is expressed directly (or indirectly by referring to a profile) by means of a ttp:extension element where the value of its value attribute is required or use, respectively.

An example of an author defined additive, derived profile of the DFXP Presentation profile is shown below in Example Fragment – DFXP Additive Profile.

Example Fragment – DFXP Additive Profile
<tt xml:lang="" xmlns="http://www.w3.org/ns/ttml">
 <head>
   <profile use="dfxp-presentation" xmlns="http://www.w3.org/ns/ttml#parameter">
     <features xml:base="http://www.w3.org/ns/ttml/feature/">
       <feature value="required">#fontStyle-italic</feature>
     </features>
   </profile>
 </head>
 <body/>
</tt>

Note:

In the above example, the baseline profile is declared to be the DFXP Presentation profile, which is then additively modified by making the #fontStyle-italic feature required (rather than optional as it is defined in F.2 DFXP Presentation Profile). Note also the resetting of the default XMLNS binding on the profile element to the TT Parameter Namespace.

5.3 Catalog

The vocabulary of the Timed Text Markup Language (TTML) is defined in the following major catalogs (divisions of vocabulary):

The core catalog defines the baseline, core vocabulary of TTML, and, in particular, the vocabulary of TTML Content. The extension catalog serves as a placeholder for extensions to the core vocabulary defined by TTML.

5.3.1 Core Catalog

The core vocabulary catalog is intended to satisfy the needs of TTML while providing a baseline vocabulary for future profiles. This vocabulary is divided into distinct categories, specified in detail in the following sections:

The core element vocabulary specified for use with a Document Instance is enumerated in Table 3 – Element Vocabulary.

Table 3 – Element Vocabulary
ModuleElements
Animation set
Content body, div, p, span, br
Document tt
Head head
Layout layout, region
Metadata metadata
Metadata Items ttm:actor, ttm:agent, ttm:copyright, ttm:desc, ttm:name, ttm:title
Parameter Itemsttp:profile, ttp:features, ttp:feature, ttp:extensions, ttp:extension
Styling styling, style

Element vocabulary groups that are used in defining content models for TTML element types are enumerated in Table 4 – Element Vocabulary Groups.

Table 4 – Element Vocabulary Groups
GroupElements
Animation.class set
Block.class div | p
Inline.class span | br | #PCDATA
Metadata.class metadata | ttm:agent | ttm:copyright | ttm:desc | ttm:title
Parameters.classttp:profile

The attribute vocabulary specified for use with the core vocabulary catalog is enumerated in Table 5 – Attribute Vocabulary.

Table 5 – Attribute Vocabulary
ModuleAttributes
Core Attributes xml:id, xml:lang, xml:space
Layout region
Metadata Attributes ttm:agent, ttm:role
Parameter Attributes ttp:cellResolution, ttp:clockMode, ttp:dropMode, ttp:frameRate, ttp:frameRateMultiplier, ttp:markerMode, ttp:pixelAspectRatio, ttp:profile, ttp:subFrameRate, ttp:tickRate, ttp:timeBase
Styling style
Styling Attributes tts:backgroundColor, tts:color, tts:direction, tts:display, tts:displayAlign, tts:extent, tts:fontFamily, tts:fontSize, tts:fontStyle, tts:fontWeight, tts:lineHeight, tts:opacity, tts:origin, tts:overflow, tts:padding, tts:showBackground, tts:textAlign, tts:textDecoration, tts:textOutline, tts:unicodeBidi, tts:visibility, tts:wrapOption, tts:writingMode, tts:zIndex
Timing Attributes begin, dur, end, timeContainer

Note:

Only those attributes defined as either (1) global, i.e., namespace qualified, or (2) shared element-specific, i.e., not namespace qualified but shared across multiple element types, are listed in Table 5 – Attribute Vocabulary above.

Note:

All vocabulary defined by TTML consistently makes use of the so-called lowerCamelCase naming convention. In some cases, this results in the change of a name when the name was based upon another specification that used a different naming convention.

5.3.2 Extension Catalog

The extension vocabulary catalog is intended for use by future profiles of TTML, and is not further defined by this version of this specification.

In addition to standardized extension vocabulary, a conforming Document Instance may contain arbitrary namespace qualified elements that reside in any namespace other than those namespaces defined for use with this specification. Furthermore, a conforming Document Instance may contain arbitrary namespace qualified attributes on TTML defined vocabulary where such attributes reside in any namespace other than those defined for use with this specification.

6 Parameters

This section specifies the parameters matter of the core vocabulary catalog, where parameters are to be understood as information that is either (1) essential or (2) of significant importance for the purpose of interpreting the semantics of other types of information expressed by core vocabulary items or for establishing a Document Processing Context by means of which TTML Content can be related to an external environment.

6.1 Parameter Element Vocabulary

The following elements, all defined in the TT Parameter Namespace, specify parametric information that applies to a Document Instance or Content Processor:

6.1.1 ttp:profile

The ttp:profile element is used to specify a collection of used (mandatory and enabled), required (mandatory), and optional (voluntary) features and extensions that must or may be supported by a Content Processor in order to process a Document Instance that makes (or may make) use of such features and extensions.

Note:

The difference between a feature and an extension is where it is defined and how it is labeled: if defined in this specification (or a future revision thereof) and labeled with a feature designation in D Features, then it is considered to be a feature; if defined in another specification and labeled there with an extension designation, then it is considered to be an extension. In general, features are expected to be defined by the W3C standards process, while extensions are expected to be defined by third parties.

This specification defines two distinct uses of the ttp:profile element:

  • as a child of the head element within a TTML Document Instance;

  • as the root element of a TTML Profile Definition Document instance;

When a ttp:profile element appears within a TTML Document Instance, its purpose is to express authorial intentions about which features and extensions must or may be supported by a recipient content processor. In addition, the element indirectly expresses information about the set of features or extensions that are (or may expected to be) used by the Document Instance.

When a ttp:profile element is used by a TTML Profile Definition Document instance, it serves to publish a machine readable specification of a specific TTML profile, of which this specification defines three such Profile Definition Documents in F Profiles.

The ttp:profile element accepts as its children zero or more elements in the Metadata.class element group, followed by zero or more ttp:features elements, followed by zero or more ttp:extensions elements.

XML Representation – Element Information Item: ttp:profile
<ttp:profile
  use = string
  xml:id = ID
  {any attribute not in default or any TT namespace}>
  Content: Metadata.class*, ttp:features*, ttp:extensions*
</ttp:profile>

If specified, the use attribute must adhere to the xsd:anyURI data type defined by [XML Schema Part 2], §3.2.17, and, furthermore, must denote a profile designator in accordance with 5.2 Profiles. In this case, the profile designator must refer to (1) a standard, predefined Profile Definition Document as defined by F Profiles, or (2) a feasibly dereferenceable resource representing a valid Profile Definition Document instance. In either case, the referenced profile serves as the baseline profile of the specifying ttp:profile element.

If the use attribute is not specified, then the baseline profile of the ttp:profile element must be considered to be the empty (null) profile, i.e., a profile definition containing no feature or extension specifications.

The collection of features and extensions of a profile are determined according to the following ordered rules:

  1. initialize the features and extensions of the profile to the empty set;

  2. if a use attribute is present, then augment the profile with the set of features and extensions specified by the referenced baseline profile;

  3. for each ttp:feature and ttp:extension element descendant of the ttp:profile element, using a post-order traversal, merge the specified feature or extension with the features and extensions of the profile, where merging a feature or extension entails replacing an existing feature or extension specification, if it already exists, or adding a new feature or extension specification, if it does not yet exist in the profile;

A conformant TTML processor is not required to be able to dereference a Profile Definition Document that is not one of the standard, predefined profiles defined by F Profiles. Furthermore, a conformant TTML processor may make use of a built-in, static form of each standard, predefined profile so as not to require dereferencing a network resource.

If a TTML processor is unable to dereference a non-standard Profile Definition Document, then it must not further process the document without the presence of an explicit override from an end-user or some implementation specific parameter traceable to an end-user or to a user or system configuration setting. If a TTML processor aborts processing of a Document Instance due to the inability to reference a non-standard Profile Definition Document, then some end-user notification should be given unless the end-user or system has disabled such a notification, or if the processor does not permit or entail the intervention of an end-user.

The ttp:profile element is illustrated by the following example.

Example Fragment – ttp:profile
<ttp:profile use="dfxp-presentation">
  <ttp:features xml:base="http://www.w3.org/ns/ttml/feature/">
    <ttp:feature>#text-outline</ttp:feature>
  </ttp:features>
</ttp:profile>

Note:

In the above example, the DFXP presentation profile is used as the baseline profile. This baseline profile is then supersetted (thus creating an additive derived profile) by requiring support for #text-outline feature.

6.1.2 ttp:features

The ttp:features element is a container element used to group infomation about feature support requirements.

The ttp:features element accepts as its children zero or more elements in the Metadata.class element group, followed by zero or more ttp:feature elements.

XML Representation – Element Information Item: ttp:features
<ttp:features
  xml:base = string : TT Feature Namespace
  xml:id = ID
  {any attribute not in default or any TT namespace}>
  Content: Metadata.class*, ttp:feature*
</ttp:features>

If specified, the xml:base attribute must (1) adhere to the xsd:anyURI data type defined by [XML Schema Part 2], §3.2.17, (2) express an absolute URI that adheres to [XML Base] and, (3) express a feature namespace as defined by D.1 Feature Designations. If not specified, the xml:base attribute's default value applies, which is the TT Feature Namespace.

The xml:base attribute is used to permit the abbreviation of feature designation URIs expressed by child ttp:feature elements.

6.1.3 ttp:feature

The ttp:feature element is used to specify infomation about support requirements for a particular feature.

The children of the ttp:feature element must express a non-empty sequence of character information items that adheres to the xsd:anyURI data type defined by [XML Schema Part 2], §3.2.17.

XML Representation – Element Information Item: ttp:feature
<ttp:feature
  value = (optional|required|use) : required
  xml:id = ID
  {any attribute not in default or any TT namespace}>
  Content: #PCDATA
</ttp:feature>

If the URI expressed by the content of the ttp:feature element is a relative URI, then, when combined with the feature namespace value expressed by the xml:base attribute of the nearest ancestor ttp:features element, it must express an absolute URI. In either case (original absolute URI or resulting absolutized URI), the URI expressed by the ttp:feature element must further adhere to the syntax of a feature designation as defined by D.1 Feature Designations, and, furthermore, the specific designation that appears in this URI, i.e., the portion of the feature designation that starts with the fragment identifier separator '#', must be defined by this specification or some published version thereof (that has achieved REC status).

If the URI expressed by the content of the ttp:feature element is a relative URI, then an xml:base attribute should be specified on the nearest ancestor ttp:features element.

The value attribute specifies whether a conforming TTML processor must or may implement the designated feature in order to process the document. If the value of the value attribute is optional, then the processor need not implement or otherwise support the feature in order to process the document; if the value is required, then the processor must implement or otherwise support the feature, irrespective of whether the feature is enabled or disabled, in order to process the document; if the value is use, then the processor must both (1) implement or otherwise support the feature and (2) have enabled (activated) use of the feature.

Note:

The default value of the value attribute is required, as indicated in the above element information item definition. Therefore, if a value attribute is not specified on a ttp:feature element, it is equivalent to specifying that support for the feature is required.

If the value of the value attribute is required or use and the TTML processor implementation does not support the feature, or if the value attribute is use and the TTML processor implementation supports but has disabled that feature, then it must not further process the document without the presence of an explicit override from an end-user or some implementation specific parameter traceable to an end-user or to a user or system configuration setting. If a TTML processor aborts processing of a Document Instance due to the specification of a required, but unsupported feature by this element, then some end-user notification should be given unless the end-user or system has disabled such a notification, or if the processor does not permit or entail the intervention of an end-user.

If the value of the value attribute is optional, and if the TTML processor implementation does not support the feature, then it may further process the document even in the case that some use of the feature is present in the document. In the case of actual use of a feature designated as optional, the default semantics associated with that feature apply; that is, the processor may behave as if the feature were not actually used or referenced by the document. Notwithstanding the above, the syntactic presence or reference to an optional feature by a document must not be considered to be a violation of document validity or a barrier to further processing if the syntactic expression is well-formed and valid.

If some defined (i.e., standardized) or otherwise well known feature is not specified by a ttp:feature element in a given profile, then it must be interpreted as if the feature were specified with the value attribute equal to optional.

Note:

In particular, if some feature is not present in a profile definition, then it is not to be interpreted as meaning the use of that feature (in a Document Instance) is disallowed or otherwise prohibited.

The ttp:feature element is illustrated by the following example.

Example Fragment – ttp:feature
<ttp:profile use="http://www.w3.org/ns/ttml/profile/dfxp-presentation">
  <ttp:features xml:base="http://www.w3.org/ns/ttml/feature/">
    <ttp:feature value="required">#fontStyle-italic</ttp:feature>
    <ttp:feature value="required">#textDecoration-under</ttp:feature>
  </ttp:features>
</ttp:profile>

Note:

In the above example, the DFXP presentation profile is used as the baseline profile. This baseline profile is then modified by two ttp:feature elements in order to superset the baseline profile (since neither #fontStyle-italic nor #textDecoration-under are required by the DFXP presentation profile).

The effect of this example is to express authorial intentions that italic font style and text underlining must be supported.

6.1.4 ttp:extensions

The ttp:extensions element is a container element used to group infomation about extension support requirements.

The ttp:extensions element accepts as its children zero or more elements in the Metadata.class element group, followed by zero or more ttp:extension elements.

XML Representation – Element Information Item: ttp:extensions
<ttp:extensions
  xml:base = string : TT Extension Namespace
  xml:id = ID
  {any attribute not in default or any TT namespace}>
  Content: Metadata.class*, ttp:extension*
</ttp:extensions>

If specified, the xml:base attribute must (1) adhere to the xsd:anyURI data type defined by [XML Schema Part 2], §3.2.17, (2) express an absolute URI that adheres to [XML Base] and, (3) express an extension namespace as defined by E.1 Extension Designations. If not specified, the xml:base attribute's default value applies, which is the TT Extension Namespace.

The xml:base attribute is used to permit the abbreviation of feature designation URIs expressed by child ttp:extension elements.

6.1.5 ttp:extension

The ttp:extension element is used to specify infomation about support requirements for a particular extension.

The children of the ttp:extension element must express a non-empty sequence of character information items that adheres to the xsd:anyURI data type defined by [XML Schema Part 2], §3.2.17.

XML Representation – Element Information Item: ttp:extension
<ttp:extension
  value = (optional|required|use) : required
  xml:id = ID
  {any attribute not in default or any TT namespace}>
  Content: #PCDATA
</ttp:extension>

If the URI expressed by the content of the ttp:extension element is a relative URI, then, when combined with the extension namespace value expressed by the xml:base attribute of the nearest ancestor ttp:extensions element, it must express an absolute URI. In either case (original absolute URI or resulting absolutized URI), the URI expressed by the ttp:extension element must further adhere to the syntax of an extension designation as defined by E.1 Extension Designations.

If the URI expressed by the content of the ttp:feature element is a relative URI, then an xml:base attribute should be specified on the nearest ancestor ttp:extensions element.

The value attribute specifies whether a conforming TTML processor must or may implement the designated extension in order to process the document. If the value of the value attribute is optional, then the processor need not implement or otherwise support the extension in order to process the document; if the value is required, then the processor must implement or otherwise support the extension in order to process the document; if the value is use, then the processor must both (1) implement or otherwise support the extension and (2) enable (activate) use of the extension.

Note:

The default value of the value attribute is required, as indicated in the above element information item definition. Therefore, if a value attribute is not specified on a ttp:extension element, it is equivalent to specifying that support for the extension is required.

If the value of the value attribute is required or use and the TTML processor implementation does not support the extension, or if the value attribute is use and the TTML processor implementation supports but has disabled that extension, then it must not further process the document without the presence of an explicit override from an end-user or some implementation specific parameter traceable to an end-user or to a user or system configuration setting. If a TTML processor aborts processing of a Document Instance due to the specification of a required, but unsupported extension by this element, then some end-user notification should be given unless the end-user or system has disabled such a notification, or if the processor does not permit or entail the intervention of an end-user.

If the value of the value attribute is optional, and if the TTML processor implementation does not support the extension, then it may further process the document even in the case that some use of the extension is present in the document. In the case of actual use of an extension designated as optional, the default semantics associated with that extension apply; that is, the processor may behave as if the extension were not actually used or referenced by the document. Notwithstanding the above, the syntactic presence or reference to an optional extension by a document must not be considered to be a violation of document validity or a barrier to further processing if the syntactic expression is well-formed and valid.

If some well known extension is not specified by a ttp:extension element in a given profile, then it must be interpreted as if the extension were specified with the value attribute equal to optional.

Note:

In particular, if some extension is not present in a profile definition, then it is not to be interpreted as meaning the use of that extension (in a Document Instance) is disallowed or otherwise prohibited.

The ttp:extension element is illustrated by the following example.

Example Fragment – ttp:extension
<ttp:profile use="http://www.w3.org/ns/ttml/profile/dfxp-transformation">
  <ttp:extensions xml:base="http://example.org/ttml/extension/">
    <ttp:extension value="use">#prefilter-by-language</ttp:extension>
  </ttp:extensions>
</ttp:profile>

Note:

In the above example, the DFXP transformation profile is used as the baseline profile. This baseline profile is then supersetted by specifying that support and use is required for a private extension defined in a third party namespace.

The effect of this example is to express authorial intentions that a recipient processor must support the DFXP transformation profile and must also support and enable an extension defined by a third party.

6.2 Parameter Attribute Vocabulary

The following attributes are defined in the TT Parameter Namespace.

Unless explicitly stated otherwise, linear white-space (LWSP) must appear between adjacent non-terminal components of a TT Parameter value unless some other delimiter is permitted and used.

6.2.1 ttp:cellResolution

The ttp:cellResolution attribute may be used by an author to express the number of horizontal and vertical cells into which the Root Container Region area is divided for the purpose of expressing presentation semantics in terms of a uniform grid.

If specified, the value of this attribute must adhere to the following syntax:

Syntax Representation – ttp:cellResolution
ttp:cellResolution
  : columns rows                            // columns != 0; rows != 0

columns | rows
  : <digit>+

If not specified, the number of columns and rows must be considered to be 32 and 15, respectively. If specified, then columns or rows must not be zero (0).

Note:

The choice of values 32 and 15 are based on this being the maximum number of columns and rows defined by [CEA-608-E].

A ttp:cellResolution attribute is considered to be significant only when specified on the tt element.

Note:

The use of a uniform grid is employed only for the purpose of measuring lengths and expressing coordinates. In particular, it is not assumed that the presentation of text or the alignment of individual glyph areas is coordinated with this grid. Such alignment is possible, but requires the use of a monospaced font and a font size whose EM square exactly matches the cell size.

Except where indicated otherwise, when a <length> expressed in cells denotes a dimension parallel to the inline or block progression dimension, the cell's dimension in the inline or block progression dimension applies, respectively.

Note:

For example, if padding (on all four edges) is specified as 0.1c, the cell resolution is 20 by 10, and the extent of the Root Container Region is 640 by 480, then, assuming top to bottom, left to right writing mode, the start and end padding will be (640 / 20) * 0.1 pixels and the before and after padding will be (480 / 10) * 0.1 pixels.

6.2.2 ttp:clockMode

The ttp:clockMode attribute is used to specify the interpretation of time expressions as real-time time coordinates when operating with time base of clock as defined by 6.2.11 ttp:timeBase.

Note:

See 10.3 Time Value Expressions for the specification of time expression syntax and semantics.

If specified, the value of this attribute must adhere to the following syntax:

Syntax Representation – ttp:clockMode
ttp:clockMode
  : "local"
  | "gps"
  | "utc"

If the time base, defined by 6.2.11 ttp:timeBase, is designated as clock, then this parameter applies as follows: if the parameter's value is local, then time expressions are interpreted as local wall-clock time coordinates; if utc, then time expressions are interpreted as UTC time coordinates [UTC]; if gps, then time expressions are interpreted as GPS time coordinates [GPS].

Note:

The primary difference between GPS time and UTC time is that GPS time is not adjusted for leap seconds, while UTC time is adjusted as follows: UTC = TAI (Temp Atomique International) + leap seconds accumulated since 1972. TAI is maintained by the Bureau International des Poids et Mesures (BIPM) in Sevres, France. The GPS system time is steered to a Master Clock (MC) at the US Naval Observatory which is kept within a close but unspecified tolerance of TAI.

If not specified, the value of this parameter must be considered to be utc.

A ttp:clockMode attribute is considered to be significant only when specified on the tt element.

6.2.3 ttp:dropMode

The ttp:dropMode attribute is used to specify constraints on the interpretation and use of frame counts that correspond with [SMPTE 12M] time coordinates when operating with time base of smpte as defined by 6.2.11 ttp:timeBase.

If specified, the value of this attribute must adhere to the following syntax:

Syntax Representation – ttp:dropMode
ttp:dropMode
  : "dropNTSC"
  | "dropPAL"
  | "nonDrop"

If the time base, defined by 6.2.11 ttp:timeBase, is designated as smpte, then this parameter applies as follows: if the parameter's value is nonDrop, then, within any given second of a time expression, frames count from 0 to N−1, where N is the value specified by the ttp:frameRate parameter, but while ignoring any value specified by the ttp:frameRateMultiplier parameter.

Note:

When operating in nonDrop mode, a second of a time expression may or may not be equal to a second of real time during normal (1x speed) forward playback. If the ttp:frameRateMultiplier parameter is specified and is not equal to 1:1, then a second of a time expression will either be shorter or longer than a second of elapsed play in real time.

Note:

See 10.3 Time Value Expressions regarding the absence of defined semantics for both the offset-time form and the fraction component of time expressions when the smpte time base applies.

If this parameter's value is dropNTSC, then, within any given second of a time expression except the second 00, frames count from 0 to N−1, where N is the value specified by the ttp:frameRate parameter, but while ignoring any value specified by the ttp:frameRateMultiplier parameter. If the second of a time expression is 00 and the minute of the time expression is not 00, 10, 20, 30, 40, or 50, then frame codes 00 and 01 are dropped during that second; otherwise, these frame codes are not dropped.

Note:

For example, when operating in dropNTSC mode with ttp:frameRate of 30, a discontinuity in frame count occurs between consecutive frames as shown in the following sequence of time expressions: 01:08:59:28, 01:08:59:29, 01:09:00:02, 01:09:00:03.

If this parameter's value is dropPAL, then, within any given second of a time expression except the second 00, frames count from 0 to N−1, where N is the value specified by the ttp:frameRate parameter, but while ignoring any value specified by the ttp:frameRateMultiplier parameter. If the second of a time expression is 00 and the minute of the time expression is even but not 00, 20, or 40, then frame codes 00 through 03 are dropped during that second; otherwise, these frame codes are not dropped.

Note:

For example, when operating in dropPAL mode with ttp:frameRate of 30, a discontinuity in frame count occurs between consecutive frames as shown in the following sequence of time expressions: 01:09:59:28, 01:09:59:29, 01:10:00:04, 01:10:00:05.

Note:

The dropPAL mode is also known as the M/PAL or PAL (M) drop-frame code, which uses PAL modulation with the NTSC frame rate of ~29.97 frames/second. The M/PAL system is used primarily in Brazil.

If not specified, then nonDrop must be assumed to apply.

A ttp:dropMode attribute is considered to be significant only when specified on the tt element.

6.2.4 ttp:frameRate

The ttp:frameRate attribute is used to specify the frame rate of a related media object or the intrinsic frame rate of a Document Instance in case it is intended to function as an independent media object.

If specified, the value of this attribute must adhere to the following syntax:

Syntax Representation – ttp:frameRate
ttp:frameRate
  : <digit>+                                // value > 0

The frame rate that applies to a Document Instance is used to interpret time expressions that are expressed in frames as defined by 10.3.1 <timeExpression>.

If the media time base applies and the effective frame rate is integral, then a frame is interpreted as a division of a second of media time, such that if the frame rate is specified as F, then a second of media time is divided into F intervals of equal duration, where each interval is labeled as frame f, with f ∈ [0…F−1].

Note:

See N.2 Media Time Base for further details on the interpretation of time expressions for the media time base.

If not specified, the frame rate must be considered to be equal to some application defined frame rate, or if no application defined frame rate applies, then thirty (30) frames per second. If specified, then the frame rate must be greater than zero (0).

A ttp:frameRate attribute is considered to be significant only when specified on the tt element.

6.2.5 ttp:frameRateMultiplier

The ttp:frameRateMultiplier attribute is used to specify a multiplier to be applied to the frame rate specified by a ttp:frameRate attribute in order to compute the effective frame rate.

If specified, the value of this attribute must adhere to the following syntax:

Syntax Representation – ttp:frameRateMultiplier
ttp:frameRateMultiplier
  : numerator denominator                   // numerator != 0; denominator != 0

numerator | denominator
  : <digit>+

A frame rate multiplier is used when the desired frame rate cannot be expressed as an integral number of frames per second.

If not specified, the frame rate multiplier must be considered to be equal to some application defined frame rate multiplier, or if no application defined frame rate multiplier applies, then one (1:1). Both numerator and denominator must be non-zero.

A ttp:frameRateMultiplier attribute is considered to be significant only when specified on the tt element.

Note:

The frame rate multiplier used for synchronizing with NTSC [SMPTE 170M] formatted video objects at 30 frames per second is nominally 1000:1001. The nominal frame rate of NTSC video is defined as the chrominance sub-carrier frequency of 3,579,545.45…Hz (= 5.0MHz × 63/88) times the ratio 2/455 divided by the number of horizontal lines per frame of 525, which yields a frame rate of 29.970029970029… (= 30 × 1000/1001) frames per second. Other frame rate multipliers apply to different regions of usage and video format standards.

Note:

Except in the case of PAL/M, the frame rate multiplier used for synchronizing with PAL formatted video objects at 25 frames per second is nominally 1:1.

6.2.6 ttp:markerMode

The ttp:markerMode attribute is used to specify constraints on the interpretation and use of time expressions that correspond with [SMPTE 12M] time coordinates when operating with time base of smpte as defined by 6.2.11 ttp:timeBase.

If specified, the value of this attribute must adhere to the following syntax:

Syntax Representation – ttp:markerMode
ttp:markerMode
  : "continuous"
  | "discontinuous"

If the time base, defined by 6.2.11 ttp:timeBase, is designated as smpte, then this parameter applies as follows: if the parameter's value is continuous, then [SMPTE 12M] time coordinates may be assumed to be linear and either monotonically increasing or decreasing; however, if discontinuous, then any assumption must not be made regarding linearity or monotonicity of time coordinates.

If not specified, the value of this parameter must be considered to be discontinuous.

Note:

The default value for this parameter was originally specified (in TTML 1.0 First Edition) as continuous; however, further evaluation of the state of the industry indicates this choice was incorrect, and that the most common default is discontinuous.

Note:

Due to lack of industry consensus on the utility and interpretation of the continuous marker mode, authors are advised to avoid its use. Furthermore, the ttp:markerMode is being considered for deprecation in the next revision of this specification.

A ttp:markerMode attribute is considered to be significant only when specified on the tt element.

If a value of continuous applies, then time expressions may be converted to real time coordinates by taking into account the computed frame rate and drop mode as expressed by the ttp:dropMode parameter. In this case, the Content Processor must create and maintain a Synthetic SMPTE Document Syncbase within which these time expressions are interpreted as further described in 10.4 Time Intervals.

Note:

When operating with smpte time base and continuous marker mode, there is an implied time coordinate space, the Synthetic SMPTE Document Syncbase, defined by the monotonically increasing (or decreasing) [SMPTE 12M] time coordinates, while taking into account the computed frame rate and drop mode. All time expressions are interpreted in relationship to this time coordinate space based upon SMPTE Time Code synchronization events (markers), where the Document Processing Context emits these events with implied constraints regarding time coordinate monoticity and resynchronization in the presence of dropped frames.

Use of continuous marker mode with the smpte time base is different from using the media time base because (1) the semantics of the ttp:dropMode parameter apply to the former, but not the latter, and (2) [SMPTE 12M] time coordinates may be applied monotonically to media which has been subjected to dilation in time, constriction in time, or reversal in time.

If a value of discontinuous applies, then time expressions must not be converted to real time coordinates, arithmetical operators (addition, multiplication) are not defined on time expressions, and, consequently, any (well-formed) expression of a duration must be considered to be invalid.

Note:

When operating with smpte time base and discontinuous marker mode, there is no effective time coordinate space; rather, all time expressions are interpreted as labeled synchronization events (markers), where the Document Processing Context emits these events, which, when they correspond with time expressions that denote the same label, cause a temporal interval to begin or end accordingly.

An additional side-effect of operating in discontinuous mode is that time expressions of children have no necessary relationship with time expressions of their temporal container; that is, temporal containers and children of these containers are temporally activated and inactivated independently based on the occurrence of a labeled synchronization (marker) event.

Note:

The notion of marker discontinuity as captured by this parameter is logically independent from the method used to count frames as expressed by the ttp:dropMode parameter. In particular, even if the ttp:dropMode parameter is specified as dropNTSC or dropPAL, the marker mode may be specified as continuous, even in the presence of frame count discontinuities induced by the frame counting method, unless there were some other non-linearity or discontinuity in marker labeling, for example, two consecutive frames labeled as 10:00:00:00 and 10:00:01:00.

6.2.7 ttp:pixelAspectRatio

The ttp:pixelAspectRatio attribute may be used by a content author to express the aspect ratio of non-square pixels in the production of content that makes use of pixel coordinates.

If specified, the value of this attribute must adhere to the following syntax:

Syntax Representation – ttp:pixelAspectRatio
ttp:pixelAspectRatio
  : width height                            // width != 0; height != 0

width | height
  : <digit>+

If not specified, then square pixels (i.e., aspect ratio 1:1) must be assumed to apply. If specified, then both width and height must be non-zero.

A ttp:pixelAspectRatio attribute is considered to be significant only when specified on the tt element.

Note:

This parameter may be used by a content transcoder or translator in order to convert pixel measurements between different pixel aspect ratios while still maintaining authorial layout intentions.

6.2.8 ttp:profile

The ttp:profile attribute may be used by a content author to express the profile of the Timed Text Markup Language (TTML) used in a Document Instance.

If specified, the value of this attribute must adhere to the xsd:anyURI data type defined by [XML Schema Part 2], §3.2.17, and, further, must specify a profile designator in accordance with 5.2 Profiles.

A ttp:profile attribute is considered to be significant only when specified on the tt element.

6.2.9 ttp:subFrameRate

The ttp:subFrameRate attribute is used to specify the sub-frame rate of a related media object or the intrinsic sub-frame rate of a Document Instance in case it is intended to function as an independent media object.

If specified, the value of this attribute must adhere to the following syntax:

Syntax Representation – ttp:subFrameRate
ttp:subFrameRate
  : <digit>+                                // value > 0

The sub-frame rate that applies to a Document Instance is used to interpret time expressions that are expressed in sub-frames as defined by 10.3.1 <timeExpression>.

If the media time base applies and the effective frame rate is integral, a sub-frame is interpreted as a division of a frame of media time, such that if the sub-frame rate is specified as S, then a frame of media time is divided into S intervals of equal duration, where each interval is labeled as sub-frame s, with s ∈ [0…S−1].

Note:

See N.2 Media Time Base for further details on the interpretation of time expressions for the media time base.

If not specified, the sub-frame rate must be considered to be equal to some application defined sub-frame rate, or if no application defined sub-frame rate applies, then one (1). If specified, then the sub-frame rate must be greater than zero (0).

A ttp:subFrameRate attribute is considered to be significant only when specified on the tt element.

Note:

The sub-frame is sometimes referred to as a field in the context of synchronization with an interlaced video media object.

6.2.10 ttp:tickRate

The ttp:tickRate attribute is used to specify the tick rate of a related media object or the intrinsic tick rate of content of a Document Instance in case it is intended to function as an independent media object.

If specified, the value of this attribute must adhere to the following syntax:

Syntax Representation – ttp:tickRate
ttp:tickRate
  : <digit>+                                // value > 0

The tick rate that applies to a Document Instance is used to interpret time expressions that are expressed in ticks by using the t metric as defined by 10.3.1 <timeExpression>.

If the media time base applies, a tick is interpreted as an integral division of a second of media time, such that if the tick rate is specified as T, then a second of media time is divided into T intervals of equal duration, where each interval is labeled as tick t, with t ∈ [0…T−1].

Note:

See N.2 Media Time Base for further details on the interpretation of time expressions for the media time base.

If not specified, then if a frame rate is specified, the tick rate must be considered to be the effective frame rate multiplied by the sub-frame rate (i.e., ticks are interpreted as sub-frames); or, if no frame rate is specified, the tick rate must be considered to be one (1) tick per second of media time. If specified, then the tick rate must not be zero (0).

Note:

There is no predefined relationship between ticks and frames or sub-frames. Ticks are an arbitrary division of seconds that permit use of fixed point arithmetic rather than fractional (and potentially inexact) expressions of seconds.

A ttp:tickRate attribute is considered to be significant only when specified on the tt element.

6.2.11 ttp:timeBase

The ttp:timeBase attribute is used to specify the temporal coordinate system by means of which time expressions are interpreted in a Document Instance.

If specified, the value of this attribute must adhere to the following syntax:

Syntax Representation – ttp:timeBase
ttp:timeBase
  : "media"
  | "smpte"
  | "clock"

If the time base is designated as media, then a time expression denotes a coordinate in some media object's time line, where the media object may be an external media object with which the content of a Document Instance is to be synchronized, or it may be the content of a Document Instance itself in a case where the timed text content is intended to establish an independent time line.

Note:

When using a media time base, if that time base is paused or scaled positively or negatively, i.e., the media play rate is not unity, then it is expected that the presentation of associated Timed Text content will be similarly paused, accelerated, or decelerated, respectively. The means for controlling an external media time base is outside the scope of this specification.

If the time base is designated as smpte, then a time expression denotes a [SMPTE 12M] time coordinate with which the content of a Document Instance is to be synchronized. In this case, the value of the ttp:markerMode and ttp:dropMode parameters apply, as defined by 6.2.6 ttp:markerMode and 6.2.3 ttp:dropMode, respectively.

Note:

When the time base is designated as smpte, every time expression denotes a media marker value akin to that defined by [SMIL 2.1], § 10.4.1, except instead of using an opaque marker name, a structured [SMPTE 12M] time coordinate serves as the marker name.

If the time base is designated as clock, then the time expression denotes a coordinate in some real-world time line as established by some real-time clock, such as the local wall-clock time or UTC (Coordinated Universal Time) or GPS (Global Positioning System) time lines.

If not specified, the default time base must be considered to be media.

A ttp:timeBase attribute is considered to be significant only when specified on the tt element.

When operating with either media or smpte time bases, a diachronic presentation of a Document Instance may be subject to transformations of the controlling time line, such as temporal reversal, dilation (expansion), or constriction (compression); however, when operating with the clock time base, no transformations are permitted, and diachronic presentation proceeds on a linear, monotonically increasing time line based on the passage of real time.

Note:

Due to there being only one time base parameter that applies to a given Document Instance, the interpretation of time expressions is uniform throughout the Document Instance.

Note:

See N Time Expression Semantics for further details on the interpretation of time expressions according to the designated time base.

7 Content

This section specifies the content matter of the core vocabulary catalog.

7.1 Content Element Vocabulary

The following elements specify the structure and principal content aspects of a Document Instance:

7.1.1 tt

The tt element serves as the root document element of a Document Instance.

The tt element accepts as its children zero or one head element followed by zero or one body element.

XML Representation – Element Information Item: tt
<tt
  tts:extent = string
  xml:id = ID
  xml:lang = string
  xml:space = (default|preserve) : default
  {any attribute in TT Parameter namespace}
  {any attribute not in default or any TT namespace}>
  Content: head?, body?
</tt>

The Root Temporal Extent, i.e., the time interval over which a Document Instance is active, has an implicit duration that is equal to the implicit duration of the body element of the document, if the body element is present, or zero, if the body element is absent.

If the tts:extent attribute is specified on the tt element, then it must adhere to 8.2.7 tts:extent, in which case it specifies the spatial extent of the Root Container Region in which content regions are located and presented. If no tts:extent attribute is specified, then the spatial extent of the Root Container Region is considered to be determined by the Document Processing Context. The origin of the Root Container Region is determined by the Document Processing Context.

Note:

In the absence of other requirements, and if a Related Media Object exists, then it is recommended that the Document Processing Context determine that:

  • if no tts:extent is specified on the root tt element, the extent of the Root Container Region be established as equal to the extent of the Related Media Object Region; and

  • the origin of the Root Container Region be established so that this region is centered in the Related Media Object Region.

Note:

If an author desires to signal the (storage or image) aspect ratio of the Root Container Region without specifying its resolution, then this may be accomplished by using metadata specified in an external namespace, such as m708:aspectRatio as defined in [SMPTE 2052-11], §5.4.4. This would permit, for example, the interchange of information that reflects the the semantics of [CEA-708-E] , §4.5 “Caption Service Metadata”, “ASPECT RATIO”.

An xml:lang attribute must be specified on the tt element. If the attribute value is empty, it signifies that there is no default language that applies to the text contained within the Document Instance.

If no xml:space attribute is specified upon the tt element, then it must be considered as if the attribute had been specified with a value of default.

7.1.2 head

The head element is a container element used to group header matter, including metadata, profile, styling, and layout information.

The head element accepts as its children zero or more elements in the Metadata.class element group, followed by zero or more elements in the Parameters.class element group, followed by zero or one styling element, followed by zero or one layout element.

Any metadata specified by children in the Metadata.class element group applies semantically to the Document Instance as a whole, and not just the head element.

Any parameters specified by children in the Parameters.class element group applies semantically to the Document Instance as a whole, and not just the head element.

A styling child element is used to specify style constructs that are referenced from other style constructs, by layout constructs, and by Content elements.

A layout child element is used to specify layout constructs that are referenced by Content elements.

XML Representation – Element Information Item: head
<head
  xml:id = ID
  xml:lang = string
  xml:space = (default|preserve)
  {any attribute not in default or any TT namespace}>
  Content: Metadata.class*, Parameters.class*, styling?, layout?
</head>

To the extent that time semantics apply to the content of the head element, the implied time interval of this element is defined to be coterminous with the Root Temporal Extent.

7.1.3 body

The body element functions as a logical container and a temporal structuring element for a sequence of textual content units represented as logical divisions.

The body element accepts as its children zero or more elements in the Metadata.class element group, followed by zero or more elements in the Animation.class element group, followed by zero or more div elements.

Any metadata specified by children in the Metadata.class element group applies semantically to the body element and its descendants as a whole.

Any animation elements specified by children in the Animation.class element group apply semantically to the body element.

XML Representation – Element Information Item: body
<body
  begin = <timeExpression>
  dur = <timeExpression>
  end = <timeExpression>
  region = IDREF
  style = IDREFS
  timeContainer = (par|seq)
  xml:id = ID
  xml:lang = string
  xml:space = (default|preserve)
  {any attribute in TT Metadata namespace}
  {any attribute in TT Style namespace}
  {any attribute not in default or any TT namespace}>
  Content: Metadata.class*, Animation.class*, div*
</body>

An author may specify a temporal interval for a body element using the begin, dur, and end attributes. If the begin point of this interval remains unspecified, then the begin point is interpreted as the beginning point of the Root Temporal Extent. Similarly, if the end point of this interval remains unspecified, then the end point is interpreted as the ending point of the Root Temporal Extent.

Note:

A Document Instance referenced from a SMIL presentation is expected to follow the same timing rules as apply to other SMIL media objects.

If relative begin or end times are specified on the body element, then these times are resolved by reference to the beginning and ending time of the Root Temporal Extent.

If the Root Temporal Extent is shorter than the computed duration of the body element, then the active time interval of a body element is truncated to the active end point of the Root Temporal Extent.

An author may associate a set of style properties with a body element by means of either the style attribute or inline style attributes or a combination thereof.

Note:

Style properties that are associated with a body element in a Document Instance are available for style inheritance by descendant Content elements such as div, p, span and br.

If no timeContainer attribute is specified on a body element, then it must be interpreted as having parallel time containment semantics.

7.1.4 div

The div element functions as a logical container and a temporal structuring element for a sequence of textual content units represented as logical sub-divisions or paragraphs.

Note:

When rendered on a continuous (non-paged) visual presentation medium, a div element is expected to generate one or more block areas that contain zero or more child block areas generated by the div element's descendant p elements.

If some block area generated by a div element does not contain any child areas, then it is not expected to be presented.

The div element accepts as its children zero or more elements in the Metadata.class element group, followed by zero or more elements in the Animation.class element group, followed by zero or more div or p elements.

Any metadata specified by children in the Metadata.class element group applies semantically to the div element and its descendants as a whole.

Any animation elements specified by children in the Animation.class element group apply semantically to the div element.

XML Representation – Element Information Item: div
<div
  begin = <timeExpression>
  dur = <timeExpression>
  end = <timeExpression>
  region = IDREF
  style = IDREFS
  timeContainer = (par|seq)
  xml:id = ID
  xml:lang = string
  xml:space = (default|preserve)
  {any attribute in TT Metadata namespace}
  {any attribute in TT Style namespace}
  {any attribute not in default or any TT namespace}>
  Content: Metadata.class*, Animation.class*, Block.class*
</div>

An author may associate a set of style properties with a div element by means of either the style attribute or inline style attributes or a combination thereof.

Note:

Style properties that are associated with a div element in a Document Instance are available for style inheritance by descendant Content elements such as div, p, span, and br.

If no timeContainer attribute is specified on a div element, then it must be interpreted as having parallel time containment semantics.

7.1.5 p

A p element represents a logical paragraph, serving as a transition between block level and inline level formatting semantics.

The p element accepts as its children zero or more elements in the Metadata.class element group, followed by zero or more elements in the Animation.class element group, followed by zero or more intermixed span elements, br elements, or text nodes.

Any metadata specified by children in the Metadata.class element group applies semantically to the p element and its descendants as a whole.

Any animation elements specified by children in the Animation.class element group apply semantically to the p element.

XML Representation – Element Information Item: p
<p
  begin = <timeExpression>
  dur = <timeExpression>
  end = <timeExpression>
  region = IDREF
  style = IDREFS
  timeContainer = (par|seq)
  xml:id = ID
  xml:lang = string
  xml:space = (default|preserve)
  {any attribute in TT Metadata namespace}
  {any attribute in TT Style namespace}
  {any attribute not in default or any TT namespace}>
  Content: Metadata.class*, Animation.class*, Inline.class*
</p>

An author may associate a set of style properties with a p element by means of either the style attribute or inline style attributes or a combination thereof.

Note:

Style properties that are associated with a p element in a Document Instance are available for style inheritance by descendant Content elements such as span and br.

If no timeContainer attribute is specified on a p element, then it must be interpreted as having parallel time containment semantics.

If a sequence of children of a p element consists solely of character information items, then that sequence must be considered to be an anonymous span for the purpose of applying style properties that apply to span elements.

Note:

The presentation semantics of TTML effectively implies that a p element constitutes a line break. In particular, it is associated with a block-stacking constraint both before the first generated line area and after the last generated line area. See 9.3.4 Synchronic Flow Processing for further details.

7.1.6 span

The span element functions as a logical container and a temporal structuring element for a sequence of textual content units having inline level formatting semantics.

When presented on a visual medium, a span element is intended to generate a sequence of inline areas, each containing one or more glyph areas.

The span element accepts as its children zero or more elements in the Metadata.class element group, followed by zero or more elements in the Animation.class element group, followed by zero or more intermixed span elements, br elements, or text nodes.

Any metadata specified by children in the Metadata.class element group applies semantically to the span element and its descendants as a whole.

Any animation elements specified by children in the Animation.class element group apply semantically to the span element.

XML Representation – Element Information Item: span
<span
  begin = <timeExpression>
  dur = <timeExpression>
  end = <timeExpression>
  region = IDREF
  style = IDREFS
  timeContainer = (par|seq)
  xml:id = ID
  xml:lang = string
  xml:space = (default|preserve)
  {any attribute in TT Metadata namespace}
  {any attribute in TT Style namespace}
  {any attribute not in default or any TT namespace}>
  Content: Metadata.class*, Animation.class*, Inline.class*
</span>

An author may associate a set of style properties with a span element by means of either the style attribute or inline style attributes or a combination thereof.

Note:

Style properties that are associated with a span element in a Document Instance are available for style inheritance by descendant Content elements such as span and br.

If no timeContainer attribute is specified on a span element, then it must be interpreted as having parallel time containment semantics.

7.1.7 br

The br element denotes an explicit line break.

Any metadata specified by children in the Metadata.class element group applies semantically to the br element and its descendants as a whole.

Any animation elements specified by children in the Animation.class element group apply semantically to the br element.

Note:

While permitted, the use of Animation.class children is not recommended since timing vocabulary does not apply to the br element. Instead, animating a br element can be achieved by wrapping it in an animated span element.

XML Representation – Element Information Item: br
<br
  style = IDREFS
  xml:id = ID
  xml:lang = string
  xml:space = (default|preserve)
  {any attribute in TT Metadata namespace}
  {any attribute in TT Style namespace}
  {any attribute not in default or any TT namespace}>
  Content: Metadata.class*, Animation.class*
</br>

When presented on a visual medium, the presence of a br element must be interpreted as a forced line break.

Note:

The visual presentation of a br element is intended to produce the same effect as the control character CR (U+000D) followed by the control code LF (U+000A) when presented on a teletype device. Therefore, two br elements in sequence will produce a different effect than a single br element.

7.2 Content Attribute Vocabulary

This section defines the following common attributes used with many or all element types in the core vocabulary catalog:

7.2.1 xml:id

The xml:id attribute is used as defined by [XML ID].

The xml:id attribute may be used with any element in the core vocabulary catalog.

7.2.2 xml:lang

The xml:lang attribute is used as defined by [XML 1.0], §2.12, Language Identification.

The xml:lang attribute must be specified on the tt element and may be specified by an instance of any other element type in the core vocabulary catalog except parameter vocabulary.

7.2.3 xml:space

The xml:space attribute is used as defined by [XML 1.0], §2.10, White Space Handling.

The xml:space attribute may be used with any element in the core vocabulary catalog except parameter vocabulary.

The semantics of the value default are fixed to mean that when performing presentation processing of a Document Instance as described by 9.3.4 Synchronic Flow Processing, processing must occur as if the following properties were specified on the affected elements of an equivalent intermediate XSL-FO document:

  • suppress-at-line-break="auto"

  • linefeed-treatment="treat-as-space"

  • white-space-collapse="true"

  • white-space-treatment="ignore-if-surrounding-linefeed"

Similarly, the semantics of the value preserve are fixed to mean that when performing presentation processing, processing must occur as if the following properties were specified on the affected elements of an equivalent intermediate XSL-FO document:

  • suppress-at-line-break="retain"

  • linefeed-treatment="preserve"

  • white-space-collapse="false"

  • white-space-treatment="preserve"

When performing other types of processing intended to eventually result in a visual presentation by means other than those described in this specification, the semantics of space collapsing and preservation as described above should be respected. For other types of processing, the treatment of the xml:space attribute is processor dependent, but should respect the semantics described above if possible.

Note:

The semantics of the above four cited XSL-FO properties are defined by by [XSL 1.1], § 7.17.3, 7.16.7, 7.16.12, and 7.16.8, respectively.

Note:

No presentation semantics are specified for the TAB (U+0009) character. Furthermore, the TAB (U+0009) character can generate a glyph area. As a result, the use of the TAB (U+0009) character in #PCDATA content within p and span elements is not recommended.

8 Styling

This section specifies the styling matter of the core vocabulary catalog, where styling is to be understood as a separable layer of information that applies to content and that denotes authorial intentions about the presentation of that content.

Styling attributes are included in TTML to enable authorial intent of presentation to be included within a self-contained document. This section describes the semantics of style presentation in terms of a standard processing model. TTML Processors are not required to present Document Instances in any particular way; but an implementation of this model by a TTML Presentation Processor that provides externally observable results that are consistent with this model is likely to lead to a user experience that closely resembles the experience intended by the documents' authors.

Note:

The semantics of TTML style presentation are described in terms of the layout and formatting model defined in [XSL 1.1]. The effects of the attributes in this section are intended to be compatible with this model; however, presentation agents may use any technology to satisfy the authorial intent of the document. For example, a [CSS2] processor may be used to implement features it has in common with this model.

No normative use of an <?xml-stylesheet ... ?> processing instruction is defined by this specification.

8.1 Styling Element Vocabulary

The following elements specify the structure and principal styling aspects of a Document Instance:

8.1.1 styling

The styling element is a container element used to group styling matter, including metadata that applies to styling matter.

The styling element accepts as its children zero or more elements in the Metadata.class element group, followed by zero or more style elements.

XML Representation – Element Information Item: styling
<styling
  xml:id = ID
  xml:lang = string
  xml:space = (default|preserve)
  {any attribute not in default or any TT namespace}>
  Content: Metadata.class*, style*
</styling>

To the extent that time semantics apply to the content of the styling element, the implied time interval of this element is defined to be coterminous with the Root Temporal Extent.

8.1.2 style

The style element is used to define a set of style specifications expressed as a specified style set in accordance with 8.4.4.2 Specified Style Set Processing.

XML Representation – Element Information Item: style
<style
  style = IDREFS
  xml:id = ID
  xml:lang = string
  xml:space = (default|preserve)
  {any attribute in TT Style namespace}
  {any attribute not in default or any TT namespace}>
 Content: EMPTY
</style>

If a style element appears as a descendant of a region element, then the style element must be ignored for the purpose of computing referential styles as defined by 8.4.1.2 Referential Styling and 8.4.1.3 Chained Referential Styling.

Note:

That is to say, when referential styling is used by an element to refer to a style element, then the referenced style element must appear as a descendant of the styling element, and not in any other context.

8.2 Styling Attribute Vocabulary

This section defines the 8.2.1 style attribute used with both style definition elements as well as Content elements.

In addition, this section specifies the following attributes in the TT Style Namespace for use with style definition elements, certain layout elements, and Content elements that support inline style specifications:

Unless explicitly stated otherwise, linear white-space (LWSP) must appear between adjacent non-terminal components of a value of a TT Style or TT Style Extension Property value unless some other delimiter is permitted and used.

Note:

This specification makes use of lowerCamelCased local names for style attributes that are based upon like-named properties defined by [XSL 1.1]. This convention is likewise extended to token values of such properties.

Note:

A style property may be expressed as a specified attribute on any Content element type independently of whether the property applies to that element type. This capability permits the expression of an inheritable style property on ancestor elements to which the property does not apply.

Note:

Due to the general syntax of this specification (and the schemas it references) with respect to how style attributes are specified, particularly for the purpose of supporting inheritance, it is possible for an author to inadvertently specify a non-inheritable style attribute on an element that applies neither to that element or any of its descendants while still remaining conformant from a content validity perspective. Content authors may wish to make use of TTML content verification tools that detect and warn about such usage.

8.2.1 style

The style attribute is used by referential style association to reference one or more style elements each of which define a style (property) set.

The style attribute may be specified by an instance of the following element types:

If specified, the value of a style attribute must adhere to the IDREFS data type defined by [XML Schema Part 2], § 3.3.10, and, furthermore, each IDREF must reference a style element which has a styling element as an ancestor.

If the same IDREF, ID1, appears more than one time in the value of a style attribute, then there should be an intervening IDREF, ID2, where ID2 is not equal to ID1.

Note:

This constraint is intended to discourage the use of redundant referential styling while still allowing the same style to be referenced multiple times in order to potentially override prior referenced styles, e.g., when an intervening, distinct style is referenced in the IDREFS list.

Note:

See the specific element type definitions that permit use of the style attribute, as well as 8.4.1.2 Referential Styling and 8.4.1.3 Chained Referential Styling, for further information on its semantics.

8.2.2 tts:backgroundColor

The tts:backgroundColor attribute is used to specify a style property that defines the background color of a region or an area generated by content flowed into a region.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: <color>
Initial:transparent
Applies to: body, div, p, region, span
Inherited:no
Percentages:N/A
Animatable:discrete

For the purpose of determining applicability of this style property, each character child of a p element is considered to be enclosed in an anonymous span.

The tts:backgroundColor style is illustrated by the following example.

Example Fragment – Background Color
<region xml:id="r1">
  <style tts:extent="306px 114px"/>
  <style tts:backgroundColor="red"/>
  <style tts:color="white"/>
  <style tts:displayAlign="after"/>
  <style tts:padding="3px 40px"/>
</region>
...
<p region="r1" tts:backgroundColor="purple" tts:textAlign="center">
  Twinkle, twinkle, little bat!<br/>
  How <span tts:backgroundColor="green">I wonder</span> where you're at!
</p>

Example Rendition – Background Color
TTML backgroundColor style property

Note:

The semantics of the style property represented by this attribute are based upon that defined by [XSL 1.1], § 7.8.2.

8.2.3 tts:color

The tts:color attribute is used to specify a style property that defines the foreground color of marks associated with an area generated by content flowed into a region.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: <color>
Initial:see prose
Applies to: span
Inherited:yes
Percentages:N/A
Animatable:discrete

For the purpose of determining applicability of this style property, each character child of a p element is considered to be enclosed in an anonymous span.

The initial value of the tts:color property is considered to be implementation dependent. In the absence of end-user preference information, a conformant presentation processor should use an initial value that is highly contrastive to the background color of the Root Container Region.

The tts:color style is illustrated by the following example.

Example Fragment – Color
<region xml:id="r1">
  <style tts:backgroundColor="black"/>
  <style tts:color="white"/>
  <style tts:displayAlign="after"/>
  <style tts:textAlign="center"/>
</region>
...
<p region="r1">
  In spring, when woods are <span tts:color="green">getting green</span>,<br/>
  I'll try and tell you what I mean.
</p>

Example Rendition – Color
TTML color style property

Note:

The semantics of the style property represented by this attribute are based upon that defined by [XSL 1.1], § 7.18.1.

8.2.4 tts:direction

The tts:direction attribute is used to specify a style property that, depending on the context of use, determines (1) the bidirectional paragraph level, or (2) the directionality of a bidirectional embedding or override.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: ltr | rtl
Initial: ltr
Applies to: p, span
Inherited:yes
Percentages:N/A
Animatable:discrete

For the purpose of determining applicability of this style property, each character child of a p element is considered to be enclosed in an anonymous span.

When applied to a p element, the computed value of this property explicitly establishes the paragraph level as specified by [UAX9], § 4.3, Higher Level Protocol HL1.

When applied to a span element (or anonymous span), the computed value of this property, in combination with the computed value of the tts:unicodeBidi style property, determines the directionality of a bidirectional embedding or override as specified by [UAX9], § 4.3, Higher Level Protocol HL3.

If a computed value of the property associated with this attribute is not supported, then a presentation processor must use the value ltr.

The tts:direction style is illustrated by the following example.

Example Fragment – Direction
<region xml:id="r1">
  <style tts:extent="265px 84px"/>
  <style tts:padding="5px"/>
  <style tts:backgroundColor="black"/>
  <style tts:color="white"/>
  <style tts:displayAlign="after"/>
  <style tts:textAlign="center"/>
</region>
...
<p region="r1">
  Little birds are playing<br/>
  Bagpipes on the shore,<br/>
  <span tts:unicodeBidi="bidiOverride" tts:direction="rtl">where the tourists snore.</span>
</p>

Example Rendition – Direction
TTML direction style property

Note:

The semantics of the style property represented by this attribute are based upon that defined by [XSL 1.1], § 7.29.1.

8.2.5 tts:display

The tts:display attribute is used to specify a style property that defines whether an element is a candidate for layout and composition in a region.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: auto | none
Initial: auto
Applies to: body, div, p, region, span
Inherited:no
Percentages:N/A
Animatable:discrete

For the purpose of determining applicability of this style property, each character child of a p element is considered to be enclosed in an anonymous span.

If the value of this attribute is auto, then the affected element is a candidate for region layout and presentation; however, if the value is none, then the affected element and its descendants must be considered ineligible for region layout and presentation.

The tts:display style is illustrated by the following example.

Example Fragment – Display
<region xml:id="r1">
  <style tts:extent="369px 119px"
            tts:backgroundColor="black"
            tts:color="white"
            tts:displayAlign="before"
            tts:textAlign="start"/>
</region>
...
<div region="r1">
  <p dur="5s">
    [[[
    <span tts:display="none">
      <set begin="1s" dur="1s" tts:display="auto"/>
      Beautiful soup,
    </span>
    <span tts:display="none">
      <set begin="2s" dur="1s" tts:display="auto"/>
      so rich and green,
    </span>
    <span tts:display="none">
      <set begin="3s" dur="1s" tts:display="auto"/>
      waiting in a hot tureen!
    </span>
    ]]]
  </p>
</div>

Example Rendition – Display
TTML display style property - [0,1)
TTML display style property - [1,2)
TTML display style property - [2,3)
TTML display style property - [3,4)
TTML display style property - [4,5)

Note:

The semantics of the style property represented by this attribute are based upon that defined by [CSS2], § 9.2.4.

8.2.6 tts:displayAlign

The tts:displayAlign attribute is used to specify a style property that defines the alignment of block areas in the block progression direction.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: before | center | after
Initial: before
Applies to: region
Inherited:no
Percentages:N/A
Animatable:discrete

If a computed value of the property associated with this attribute is not supported, then a presentation processor must use the value before.

The tts:displayAlign style is illustrated by the following example.

Example Fragment – Display Align
<region xml:id="r1">
  <style tts:extent="128px 66px" tts:origin="0px 0px"
       tts:backgroundColor="black" tts:color="white"/>
  <style tts:displayAlign="before"/>
  <style tts:textAlign="start"/>
</region>
<region xml:id="r2">
  <style tts:extent="192px 66px" tts:origin="128px 66px"/>
       tts:backgroundColor="green" tts:color="white"/>
  <style tts:displayAlign="after"/>
  <style tts:textAlign="start"/>
</region>
<region xml:id="r3">
  <style tts:extent="128px 66px"/> style tts:origin="0px 132px"
       tts:backgroundColor="black" tts:color="white"/>
  <style tts:displayAlign="before"/>
  <style tts:textAlign="start"/>
</region>
<region xml:id="r4">
  <style tts:extent="192px 66px" tts:origin="128px 198px"/>
       tts:backgroundColor="green" tts:color="white"/>
  <style tts:displayAlign="after"/>
  <style tts:textAlign="start"/>
</region>
...
<div>
  <p region="r1">I sent a message to the fish:</p>
  <p region="r2">I told them<br/> "This is what I wish."</p>
  <p region="r3">The little fishes of the sea,</p>
  <p region="r4">They sent an<br/> answer back to me.</p>
</div>

Example Rendition – Display Align
TTML displayAlign style property

Note:

The semantics of the style property represented by this attribute are based upon that defined by [XSL 1.1], § 7.14.4.

8.2.7 tts:extent

The tts:extent attribute is used to specify the width and height of a region area (which may be the Root Container Region).

Note:

If padding is applied to a region, then the region's extent includes that padding, i.e., padding is applied as an inset, and, therefore, is interior to the region's extent.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: auto | <length> <length>
Initial:auto
Applies to: tt, region
Inherited:no
Percentages:relative to width and height of Root Container Region
Animatable:discrete

If the value of this attribute consists of two <length> specifications, then they must be interpreted as width and height, where the first specification is the width, and the second specification is the height.

The <length> value(s) used to express extent must be non-negative.

If the value of this attribute is auto, then the computed value of the style property must be considered to be the same as the extent of the Root Container Region.

The extent of the Root Container Region is determined either by a tts:extent specified on the tt element, if present, or as described by 7.1.1 tt if not present. If tts:extent is specified on the tt element, then the width and height must be expressed in terms of two <length> specifications, and these specifications must be expressed as non-percentage, definite lengths using pixel units.

If a computed value of the property associated with this attribute is not supported, then a presentation processor must use the closest supported value.

Note:

In this context, the phrase closest supported value means the value for which the Euclidean distance between the computed extent and the supported extent is minimized. If there are multiple closest supported values equally distant from the computed value, then the value most distant from [0,0], i.e., of greatest extent, is used.

The tts:extent style is illustrated by the following example.

Example Fragment – Extent
<region xml:id="r1">
  <style tts:extent="330px 122px"/>
  <style tts:backgroundColor="black"/>
  <style tts:color="white"/>
  <style tts:displayAlign="after"/>
  <style tts:textAlign="center"/>
</region>
...
<p region="r1">
  'Tis the voice of the Lobster:<br/>
  I heard him declare,<br/>
  "You have baked me too brown,<br/>
  I must sugar my hair."
</p>

Example Rendition – Extent
TTML extent style property

8.2.8 tts:fontFamily

The tts:fontFamily attribute is used to specify a style property that defines the font family from which glyphs are selected for glyph areas generated by content flowed into a region.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: (<familyName> | <genericFamilyName>) (","  (<familyName> | <genericFamilyName>))*
Initial:default
Applies to: span
Inherited:yes
Percentages:N/A
Animatable:discrete

Note:

While permitted, the use of linear whitespace (LWSP) around the comma delimiters in the value of this attribute is not recommended. The rationale for this recommendation is that some existing processors may not be tolerant of this usage.

Note:

The initial value, default, is a generic font family name, and is further described in 8.3.6 <genericFamilyName> below.

For the purpose of determining applicability of this style property, each character child of a p element is considered to be enclosed in an anonymous span.

If a computed value of the property associated with this attribute is not supported, then a presentation processor must attempt to map the computed font family to a supported font family that has similar typographic characteristics, or, in the absence of such a mapping, it must use the value default.

The tts:fontFamily style is illustrated by the following example.

Example Fragment – Font Family
<region xml:id="r1">
  <style tts:extent="474px 146px"/>
  <style tts:backgroundColor="black"/>
  <style tts:color="white"/>
  <style tts:displayAlign="center"/>
  <style tts:textAlign="start"/>
  <style tts:fontFamily="proportionalSansSerif"/>
</region>
...
<div region="r1">
  <p>
    "The time has come," the Walrus said,<br/>
    "to talk of many things:
  </p>
  <p tts:textAlign="end" tts:fontFamily="monospaceSerif">
    Of shoes, and ships, and sealing wax,<br/>
    Of cabbages and kings,
  </p>
  <p>
    And why the sea is boiling hot,<br/>
    and whether pigs have wings."
  </p>
</div>

Example Rendition – Font Family
TTML fontFamily style property

Note:

The semantics of the style property represented by this attribute are based upon that defined by [XSL 1.1], § 7.9.2.

8.2.9 tts:fontSize

The tts:fontSize attribute is used to specify a style property that defines the font size for glyphs that are selected for glyph areas generated by content flowed into a region.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: <length> <length>?
Initial:1c
Applies to: span
Inherited:yes
Percentages:if not region element, then relative to parent element's font size; otherwise, relative to the Computed Cell Size
Animatable:discrete

If a single <length> value is specified, then this length applies equally to horizontal and vertical scaling of a glyph's EM square; if two <length> values are specified, then the first expresses the horizontal scaling and the second expresses vertical scaling.

Note:

Use of independent horizontal and vertical font sizes is expected to be used with cell based units in order to denote fonts that are two rows in height and one column in width.

Note:

A glyph's EM square is conventionally defined as the EM square of the font that contains the glyph. That is, glyphs do not have an EM square that is distinct from their font's EM square.

If horizontal and vertical sizes are expressed independently, then the units of the <length> values must be the same.

The <length> value(s) used to express font size must be non-negative.

For the purpose of determining applicability of this style property, each character child of a p element is considered to be enclosed in an anonymous span.

If a computed value of the property associated with this attribute is not supported, then a presentation processor must use the closest supported value.

Note:

In this context, the phrase closest supported value means the value for which the Euclidean distance between the computed font size and the supported font size is minimized. If there are multiple closest supported values equally distant from the computed value, then the value most distant from 0 (single length specification) or [0,0] (two length specifications) is used, i.e., the largest font size, is used.

Note:

The expression 1c means one cell, where 'c' expresses the cell length unit as defined by 8.3.9 <length>. When a single <length> is expressed using cell units, then it refers to the height of the Computed Cell Size. When two <length> values are expressed using cell units, then the first refers to the width of the Computed Cell Size, and the second refers to the height of the Computed Cell Size.

The tts:fontSize style is illustrated by the following example.

Example Fragment – Font Size
<region xml:id="r1">
  <style tts:extent="299px 97px"/>
  <style tts:backgroundColor="black"/>
  <style tts:color="white"/>
  <style tts:displayAlign="center"/>
  <style tts:textAlign="center"/>
  <style tts:fontFamily="proportionalSansSerif"/>
  <style tts:fontSize="18px"/>
</region>
...
<p region="r1">
  Then fill up the glasses<br/>
  with treacle and ink,<br/>
  Or anything else<br/>
  that is <span tts:fontSize="24px">pleasant</span> to drink.
</p>

Example Rendition – Font Size
TTML fontSize style property

Note:

The semantics of the style property represented by this attribute are based upon that defined by [XSL 1.1], § 7.9.4. The addition of a second length component to permit specifying font width and height independently is an extension introduced by TTML.

8.2.10 tts:fontStyle

The tts:fontStyle attribute is used to specify a style property that defines the font style to apply to glyphs that are selected for glyph areas generated by content flowed into a region, where the mapping from font style value to specific font face or style parameterization is not determined by this specification.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: normal | italic | oblique
Initial:normal
Applies to: span
Inherited:yes
Percentages:N/A
Animatable:discrete

For the purpose of determining applicability of this style property, each character child of a p element is considered to be enclosed in an anonymous span.

Use of the value oblique denotes a shear transformation (at an unspecified angle) in the inline progression dimension.

If a computed value of the property associated with this attribute is not supported, then a presentation processor must use the value normal.

The tts:fontStyle style is illustrated by the following example.

Example Fragment – Font Style
<region xml:id="r1">
  <style tts:extent="331px 84px"/>
  <style tts:backgroundColor="black"/>
  <style tts:color="white"/>
  <style tts:displayAlign="after"/>
  <style tts:textAlign="center"/>
  <style tts:fontFamily="proportionalSansSerif"/>
</region>
...
<p region="r1">
  In autumn, when the leaves are brown,<br/>
  Take pen and ink, and <span tts:fontStyle="italic">write it down.</span>
</p>

Example Rendition – Font Style
TTML fontStyle style property

Note:

The semantics of the style property represented by this attribute are based upon that defined by [XSL 1.1], § 7.9.7.

8.2.11 tts:fontWeight

The tts:fontWeight attribute is used to specify a style property that defines the font weight to apply to glyphs that are selected for glyph areas generated by content flowed into a region, where the mapping from font weight value to specific font face or weight parameterization is not determined by this specification.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: normal | bold
Initial:normal
Applies to: span
Inherited:yes
Percentages:N/A
Animatable:discrete

For the purpose of determining applicability of this style property, each character child of a p element is considered to be enclosed in an anonymous span.

If a computed value of the property associated with this attribute is not supported, then a presentation processor must use the value normal.

The tts:fontWeight style is illustrated by the following example.

Example Fragment – Font Weight
<region xml:id="r1">
  <style tts:extent="376px 95px"/>
  <style tts:backgroundColor="black"/>
  <style tts:color="white"/>
  <style tts:displayAlign="center"/>
  <style tts:textAlign="center"/>
  <style tts:fontFamily="proportionalSansSerif"/>
</region>
...
<p region="r1">
  They told me you had been to her,<br/>
  <span tts:fontWeight="bold">and mentioned me to him:</span><br/>
  She gave me a good character<br/>
  <span tts:fontWeight="bold">but said I could not swim.</span>
</p>

Example Rendition – Font Weight
TTML fontWeight style property

Note:

The semantics of the style property represented by this attribute are based upon that defined by [XSL 1.1], § 7.9.9.

8.2.12 tts:lineHeight

The tts:lineHeight attribute is used to specify a style property that defines the inter-baseline separation between line areas generated by content flowed into a region.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: normal | <length>
Initial:normal
Applies to: p
Inherited:yes. See also special inheritance semantics.
Percentages:relative to this element's font size
Animatable:discrete

If the value of this attribute is normal, then the computed value of the style property must be considered to be no less than the size of the largest font size that applies to the element and its descendant elements in the intermediate synchronic document as determined by 9.3.3 Intermediate Synchronic Document Construction.

Note:

It is recommended that presentation processors use a computed line height that is 125% of the size of the largest applicable font size when the value normal is specified. The choice of 125% allows use of a font size of 0.8c in order to obtain a line height of 1c.

If specified as a <length>, then the length must be non-negative.

If a computed value of the property associated with this attribute is not supported, then a presentation processor must use the closest supported value.

Note:

In this context, the phrase closest supported value means the value for which the Euclidean distance between the computed line height and the supported line height is minimized. If there are multiple closest supported values equally distant from the computed value, then the value most distant from 0, i.e., the largest line height, is used.

The tts:lineHeight style is illustrated by the following example.

Example Fragment – Line Height
<region xml:id="r1">
  <style tts:extent="255px 190px"/>
  <style tts:backgroundColor="black"/>
  <style tts:color="white"/>
  <style tts:displayAlign="center"/>
  <style tts:textAlign="start"/>
  <style tts:fontFamily="proportionalSansSerif"/>
  <style tts:fontSize="16px"/>
  <style tts:lineHeight="32px"/>
</region>
...
<p region="r1">
  He thought he saw an elephant,<br/>
  That practised on a fife:<br/>
  He looked again, and found it was<br/>
  A letter from his wife.<br/>
  "At length I realise," he said,<br/>
  "The bitterness of Life.
"</p>

Example Rendition – Line Height
TTML lineHeight style property

Note:

The semantics of the style property represented by this attribute are based upon that defined by [XSL 1.1], § 7.16.4. Furthermore, it is the intention of this specification that the allocation rectangle of a line be consistent with the per-inline-height-rectangle as defined by [XSL 1.1], § 4.5, i.e., that a CSS-style line box stacking strategy be used.

8.2.12.1 Special Inheritance Semantics

When the value of the attribute is normal and when applying inheritance semantics, the value normal, not the computed value, is inherited.

8.2.13 tts:opacity

The tts:opacity attribute is used to specify a style property that defines the opacity (or conversely, the transparency) of marks associated with a region.

When presented onto a visual medium, the opacity of the region is applied uniformly and on a linear scale to all marks produced by content targeted to the region.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: <alpha>
Initial: 1.0
Applies to: region
Inherited:no
Percentages:N/A
Animatable:discrete

The tts:opacity style is illustrated by the following example.

Example Fragment – Opacity
<region xml:id="r1" dur="5s">
  <set begin="0s" dur="1s" tts:opacity="1.00"/>
  <set begin="1s" dur="1s" tts:opacity="0.75"/>
  <set begin="2s" dur="1s" tts:opacity="0.50"/>
  <set begin="3s" dur="1s" tts:opacity="0.25"/>
  <set begin="4s" dur="1s" tts:opacity="0.00"/>
  <style tts:extent="304px 77px"/>
  <style tts:backgroundColor="black"/>
  <style tts:color="white"/>
  <style tts:displayAlign="after"/>
  <style tts:textAlign="center"/>
</region>
...
<p region="r1">
  The sun was shining on the sea
</p>

Example Rendition – Opacity
TTML opacity style property - [0,1)
TTML opacity style property - [1,2)
TTML opacity style property - [2,3)
TTML opacity style property - [3,4)
TTML opacity style property - [4,5)

Note:

The semantics of the style property represented by this attribute are based upon that defined by [CSS3 Color], § 3.2.

8.2.14 tts:origin

The tts:origin attribute is used to specify the x and y coordinates of the origin of a region area with respect to the origin of the Root Container Region.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: auto | <length> <length>
Initial:auto
Applies to: region
Inherited:no
Percentages:relative to width and height of Root Container Region
Animatable:discrete

If the value of this attribute consists of two <length> specifications, then they must be interpreted as x and y coordinates, where the first specification is the x coordinate, and the second specification is the y coordinate.

If the value of this attribute is auto, then the computed value of the style property must be considered to be the same as the origin of the Root Container Region.

If a computed value of the property associated with this attribute is not supported, then a presentation processor must use the closest supported value.

Note:

In this context, the phrase closest supported value means the value for which the Euclidean distance between the computed origin and the supported origin is minimized. If there are multiple closest supported values equally distant from the computed value, then the value least distant from [0,0], i.e., closest to the coordinate space origin, is used.

The tts:origin style is illustrated by the following example.

Example Fragment – Origin
<region xml:id="r1">
  <style tts:origin="40px 40px"/>
  <style tts:extent="308px 92px"/>
  <style tts:backgroundColor="black"/>
  <style tts:color="white"/>
  <style tts:displayAlign="center"/>
  <style tts:textAlign="center"/>
</region>
...
<p region="r1">
  "To dine!" she shrieked in dragon-wrath.<br/>
  "To swallow wines all foam and froth!<br/>
   To simper at a table-cloth!"
</p>

Example Rendition – Origin
TTML origin style property

8.2.15 tts:overflow

The tts:overflow attribute is used to specify a style property that defines whether a region area is clipped or not if the descendant areas of the region overflow its extent.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: visible | hidden
Initial:hidden
Applies to: region
Inherited:no
Percentages:N/A
Animatable:discrete

If the value of this attribute is visible, then content should not be clipped outside of the affected region, and region composition and layout must be performed as if the region's width and height were unconstrained, but with a well-defined origin. If the value is hidden, then content should be clipped outside of the affected region.

Note:

Unless a manual line break element br is used by the content author, a paragraph of a given region will generate no more than one line area in that region if the value of the tts:overflow style that applies to the region is visible and if the applicable tts:wrapOption style is noWrap.

If a computed value of the property associated with this attribute is not supported, then a presentation processor must use the value hidden.

The tts:overflow style is illustrated by the following example.

Example Fragment – Overflow
<?xml version="1.0"?>
<tt xmlns="http://www.w3.org/ns/ttml" xmlns:tts="http://www.w3.org/ns/ttml#styling" xml:lang="en" tts:extent="320px 240px">
  <head>
    <styling>
      <style xml:id="s1" tts:backgroundColor="black" tts:padding="6px"/>
      <style xml:id="s2" tts:color="red" tts:backgroundColor="white" tts:wrapOption="noWrap" tts:fontFamily="proportionalSansSerif" tts:fontSize="10px"/>
    </styling>
    <layout>
      <region xml:id="r1" style="s1" tts:extent="100px 40px" tts:origin="20px 20px" tts:overflow="visible"/>
      <region xml:id="r2" style="s1" tts:extent="100px 40px" tts:origin="20px 180px" tts:overflow="hidden"/>
    </layout>
  </head>
  <body>
    <div>
      <p region="r1" style="s2">
  "But wait a bit," the Oysters cried,<br/>
  "Before we have our chat;
      </p>
      <p region="r2" style="s2">
  For some of us are out of breath,<br/>
  And all of us are fat!"
      </p>
    </div>
  </body>
</tt>

Example Rendition – Overflow
TTML overflow style property

Note:

In the above example, the tts:noWrap is set to noWrap to prevent automatic line wrapping (breaking); if this were not specified, then overflow would occur in the block progression direction as opposed to the inline progression direction.

Note:

The semantics of the style property represented by this attribute are based upon that defined by [XSL 1.1], § 7.21.2.

8.2.16 tts:padding

The tts:padding attribute is used to specify padding (or inset) space on all sides of a region area.

Note:

Padding is applied as an inset to a region area, which is to say, the content rectangle of a region area is reduced by the presence of padding applied to the region.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: <length> | <length> <length> | <length> <length> <length> | <length> <length> <length> <length>
Initial:0px
Applies to: region
Inherited:no
Percentages:relative to width and height of region
Animatable:discrete

If the value of this attribute consists of one <length> specification, then that length applies to all edges of the affected areas. If the value consists of two <length> specifications, then the first applies to the before and after edges, and the second applies to the start and end edges. If three <length> specifications are provided, then the first applies to the before edge, the second applies to the start and end edges, and the third applies to the after edge. If four <length> specifications are provided, then they apply to before, end, after, and start edges, respectively.

Note:

Percentage values are relative to the dimension of the region to which they apply. For example, if the before and after edges correspond to the top and bottom edges of the region, as is the case for Latin text where tts:writingMode is equal to "lrtb", then percentage values that apply to either of the two edges are relative to the height of the region. Conversely, if the before and after edges correspond to the right and left edges of the region, as is the case for Japanese text where tts:writingMode is equal to "tbrl", then percentage values that apply to either of the two edges are relative to the width of the region.

The <length> value(s) used to express padding must be non-negative.

If a computed value of the property associated with this attribute is not supported, then a presentation processor must use the closest supported value.

Note:

In this context, the phrase closest supported value means the value for which the Euclidean distance between the computed padding and the supported padding is minimized. If there are multiple closest supported values equally distant from the computed value, then the value most distant from 0, i.e., the greatest padding, is used.

The tts:padding style is illustrated by the following example.

Example Fragment – Padding
<region xml:id="r1">
  <style tts:extent="446px 104px"/>
  <style tts:backgroundColor="black"/>
  <style tts:color="white"/>
  <style tts:displayAlign="after"/>
  <style tts:textAlign="center"/>
  <style tts:padding="10px 40px"/>
</region>
...
<p region="r1" tts:backgroundColor="red">
  Just the place for a Snark! I have said it twice:<br/>
  That alone should encourage the crew.<br/>
  Just the place for a Snark! I have said it thrice:<br/>
  What I tell you three times is true.
</p>

When rendering an area to which padding applies, the background color that applies to the area is rendered into the padded portion of the area.

Example Rendition – Padding
TTML padding style property

Note:

The above example depicts how padding is applied as an inset to a region area. In particular, 10px of padding is applied to the before (top) and after (bottom) edges, and 40px of padding is applied at the start (left) and end (right) edges. Subtracting these from the extent of the region area results in the region's content rectangle having 366px width and 84px height. The black background color of the region appears in the region's padding rectangle while the red background color of the paragraph appears in the region's content rectangle.

Note:

The semantics of the style property represented by this attribute are based upon that defined by [XSL 1.1], § 7.31.15, except that individual shorthand values map to writing mode relative padding values as defined by [XSL 1.1], § 7.8.31, 7.8.32, 7.8.33, and 7.8.34.

8.2.17 tts:showBackground

The tts:showBackground attribute is used to specify constraints on when the background color of a region is intended to be presented.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: always | whenActive
Initial:always
Applies to: region
Inherited:no
Percentages:N/A
Animatable:discrete

If the value of this attribute is always, then the background color of a region is always rendered when performing presentation processing on a visual medium; if the value is whenActive, then the background color of a region is rendered only when some content is flowed into the region.

If a computed value of the property associated with this attribute is not supported, then a presentation processor must use the value always.

The tts:showBackground style is illustrated by the following example.

Example Fragment – Show Background
<region xml:id="r1">
  <style tts:origin="0px 0px"/>
  <style tts:extent="265px 100px"/>
  <style tts:backgroundColor="black"/>
  <style tts:showBackground="always"/>
  <style tts:color="white"/>
  <style tts:displayAlign="before"/>
  <style tts:textAlign="start"/>
</region>
<region xml:id="r2">
  <style tts:origin="205px 60px"/>
  <style tts:extent="290px 100px"/>
  <style tts:backgroundColor="red"/>
  <style tts:color="white"/>
  <style tts:displayAlign="before"/>
  <style tts:textAlign="end"/>
  <style tts:showBackground="whenActive"/>
</region>

Note:

The semantics of the style property represented by this attribute are based upon that defined by [SMIL 2.1], § 5.3.3.

8.2.18 tts:textAlign

The tts:textAlign attribute is used to specify a style property that defines how inline areas are aligned within a containing block area in the inline progression direction.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: left | center | right | start | end
Initial:start
Applies to: p
Inherited:yes
Percentages:N/A
Animatable:discrete

If a computed value of the property associated with this attribute is not supported, then a presentation processor must use the value start.

The tts:textAlign style is illustrated by the following example.

Example Fragment – Text Align
<region xml:id="r1">
  <style tts:extent="355px 43px"/>
  <style tts:origin="0px 0px"/>
  <style tts:backgroundColor="black"/>
  <style tts:color="white"/>
  <style tts:textAlign="start"/>
</region>
<region xml:id="r2">
  <style tts:extent="355px 43px"/>
  <style tts:origin="0px 47px"/>
  <style tts:backgroundColor="black"/>
  <style tts:color="white"/>
  <style tts:textAlign="end"/>
</region>
...
<p region="r1">
  Beware the Jabberwock, my son!<br/>
  The jaws that bite, the claws that catch!
</p>
<p region="r2">
  Beware the Jubjub bird, and shun<br/>
  The frumious Bandersnatch!
</p>

Example Rendition – Text Align
TTML textAlign style property

Note:

The semantics of the style property represented by this attribute are based upon that defined by [XSL 1.1], § 7.16.9.

8.2.19 tts:textDecoration

The tts:textDecoration attribute is used to specify a style property that defines a text decoration effect to apply to glyph areas or other inline areas that are generated by content flowed into a region.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: none | [ [ underline | noUnderline ] || [ lineThrough | noLineThrough ] || [ overline | noOverline ] ]
Initial:none
Applies to:span
Inherited:see special semantics
Percentages:N/A
Animatable:discrete

For the purpose of determining applicability of this style property, each character child of a p element is considered to be enclosed in an anonymous span.

If a computed value of the property associated with this attribute is not supported, then a presentation processor must use the value none.

Note:

The syntax used above in defining the value of this property is based on the value component syntax defined in [CSS2], § 1.4.2.1. In essence, one or more of the values separated by || may appear in the property value in any order, such as "noUnderline overline lineThrough".

The tts:textDecoration style is illustrated by the following example.

Example Fragment – Text Decoration
<region xml:id="r1">
  <style tts:extent="385px 82px"/>
  <style tts:origin="0px 0px"/>
  <style tts:backgroundColor="black"/>
  <style tts:color="white"/>
  <style tts:padding="5px 2px"/>
  <style tts:textDecoration="underline"/>
</region>
...
<p region="r1">
  The sea was wet<span tts:textDecoration="noUnderline"> as </span>wet
  <span tts:textDecoration="noUnderline">
    could be,<br/>
    The sand was dry as dry.<br/>
    <span tts:textDecoration="lineThrough">There weren't any</span>
    You <span tts:textDecoration="lineThrough">couldn't</span>
    could not see a cloud<br/>
    Because no cloud was in the sky.
  </span>
</p>

Example Rendition – Text Decoration
TTML textDecoration style property

Note:

The semantics of the style property represented by this attribute are based upon that defined by [XSL 1.1], § 7.17.4.

8.2.19.1 Special Semantics

The computed value of the property associated with this attribute consists of a 3-tuple, each of which denotes, respectively, whether an underline, line through, or overline decoration is to be applied to the affected text. Furthermore, when applying inheritance semantics, each of these sub-values is considered to be inherited separately from the others.

Note:

For example, if the computed value of tts:textDecoration that applies to a div (division) element is the tuple (noUnderline, lineThrough, overline) and a p (paragraph) element child of that div specifies tts:textDecoration="noLineThrough", then the aggregate computed value that applies to the p element is (noUnderline, noLineThrough, overline), which value is then inherited by children of the p element.

8.2.20 tts:textOutline

The tts:textOutline attribute is used to specify a style property that defines a text outline effect to apply to glyphs that are selected for glyph areas generated by content flowed into a region.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: none | <color>? <length> <length>?
Initial:none
Applies to: span
Inherited:yes
Percentages:relative to this element's font size
Animatable:discrete

For the purpose of determining applicability of this style property, each character child of a p element is considered to be enclosed in an anonymous span.

The value of this attribute consists of an optional <color> term followed by one or two <length> terms. If a color term is present, then it denotes the outline color; if no color term is present, the computed value of the tts:color applies. The first length term denotes the outline thickness and the second length term, if present, indicates the blur radius.

When a relative <length> value is specified for outline thickness or blur radius, then it is resolved in terms of the height component of the referenced font size or Computed Cell Size.

The <length> value(s) used to express thickness and blur radius must be non-negative.

Note:

When a <length> expressed in cells is used in a tts:textOutline value, the cell's height applies. For example, if text outline thickness is specified as 0.1c, the cell resolution is 20 by 10, and the extent of the Root Container Region is 640 by 480, then the outline thickness will be a nominal 480 / 10 * 0.1 pixels, i.e., 4.8px, without taking into account rasterization effects.

If a computed value of the property associated with this attribute is not supported, then a presentation processor must use the value none.

The tts:textOutline style is illustrated by the following example.

Example Fragment – Text Outline
<region xml:id="r1">
  <style tts:backgroundColor="transparent"/>
  <style tts:color="yellow"/>
  <style tts:textOutline="black 2px 0px"/>
  <style tts:fontFamily="proportionalSansSerif"/>
  <style tts:fontSize="24px"/>
</region>
...
<p>
  How doth the little crocodile<br/>
  Improve its shining tail,<br/>
  And pour the waters of the Nile<br/>
  On every golden scale!<br/>
  How cheerfully he seems to grin,<br/>
  How neatly spreads his claws,<br/>
  And welcomes little fishes in,<br/>
  With gently smiling jaws!
</p>

Example Rendition – Text Outline
backgroundColor style property

8.2.21 tts:unicodeBidi

The tts:unicodeBidi attribute is used to specify a style property that defines a directional embedding or override according to the Unicode bidirectional algorithm.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: normal | embed | bidiOverride
Initial: normal
Applies to: p, span
Inherited:no
Percentages:N/A
Animatable:discrete

For the purpose of determining applicability of this style property, each character child of a p element is considered to be enclosed in an anonymous span.

If a computed value of the property associated with this attribute is not supported, then a presentation processor must use the value normal.

The tts:unicodeBidi style is illustrated by the following example.

Example Fragment – Unicode Bidirectionality
<region xml:id="r1">
  <style tts:extent="265px 84px"/>
  <style tts:padding="5px"/>
  <style tts:backgroundColor="black"/>
  <style tts:color="white"/>
  <style tts:displayAlign="after"/>
  <style tts:textAlign="center"/>
</region>
...
<p region="r1">
  Little birds are playing<br/>
  Bagpipes on the shore,<br/>
  <span tts:unicodeBidi="bidiOverride" tts:direction="rtl">where the tourists snore.</span>
</p>

Example Rendition – Unicode Bidirectionality
TTML unicodeBidi style property

Note:

The semantics of the style property represented by this attribute are based upon that defined by [XSL 1.1], § 7.29.6.

8.2.22 tts:visibility

The tts:visibility attribute is used to specify a style property that defines whether generated areas are visible or not when rendered on a visual presentation medium.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: visible | hidden
Initial: visible
Applies to: body, div, p, region, span
Inherited:yes
Percentages:N/A
Animatable:discrete

For the purpose of determining applicability of this style property, each character child of a p element is considered to be enclosed in an anonymous span.

The tts:visibility style has no affect on content layout or composition, but merely determines whether composed content is visible or not.

If the computed value of the property associated with this attribute is visible, then areas generated by this element are rendered visible when presented on a visual medium. If the computed value is hidden, then they are not rendered visible, i.e., they are hidden; notwithstanding the foregoing, a descendant element of a hidden element is rendered visible if the computed value of this property is visible on the descendant.

If a computed value of the property associated with this attribute is not supported, then a presentation processor must use the value visible.

The tts:visibility style is illustrated by the following example.

Example Fragment – Visibility
<region xml:id="r1">
  <style tts:extent="398px 121px"/>
  <style tts:backgroundColor="black"/>
  <style tts:color="white"/>
  <style/>
</region>
...
<p region="r1" dur="4s">
  <span tts:visibility="hidden">
    <set begin="1s" tts:visibility="visible"/>
    Curiouser
  </span>
  <span tts:visibility="hidden">
    <set begin="2s" tts:visibility="visible"/>
    and
  </span>
  <span tts:visibility="hidden">
    <set begin="3s" tts:visibility="visible"/>
    curiouser!
  </span>
</p>

Example Rendition – Visibility
TTML visibility style property - [0,1)
TTML visibility style property - [1,2)
TTML visibility style property - [2,3)
TTML visibility style property - [3,4)

Note:

The semantics of the style property represented by this attribute are based upon that defined by [XSL 1.1], § 7.30.17.

8.2.23 tts:wrapOption

The tts:wrapOption attribute is used to specify a style property that defines whether or not automatic line wrapping (breaking) applies within the context of the affected element.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: wrap | noWrap
Initial:wrap
Applies to: span
Inherited:yes
Percentages:N/A
Animatable:discrete

For the purpose of determining applicability of this style property, each character child of a p element is considered to be enclosed in an anonymous span.

If a computed value of the property associated with this attribute is not supported, then a presentation processor must use the value wrap.

The tts:wrapOption style is illustrated by the following example.

Example Fragment – Wrap Option
<region xml:id="r1">
  <style tts:extent="192px 117px"/>
  <style tts:backgroundColor="black"/>
  <style tts:color="white"/>
  <style tts:displayAlign="after"/>
  <style tts:overflow="hidden"/>
  <style tts:wrapOption="noWrap"/>
</region>
...
<p>
  I'll tell thee everything I can:<br/>
  There's little to relate.<br/>
  I saw an aged aged man,<br/>
  A-sitting on a gate.
</p>

Example Rendition – Wrap Option
TTML wrapOption style property

Note:

The semantics of the style property represented by this attribute are based upon that defined by [XSL 1.1], § 7.16.13.

8.2.24 tts:writingMode

The tts:writingMode attribute is used to specify a style property that defines the block and inline progression directions to be used for the purpose of stacking block and inline areas within a region area.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: lrtb | rltb | tbrl | tblr | lr | rl | tb
Initial:lrtb
Applies to: region
Inherited:no
Percentages:N/A
Animatable:discrete

If a computed value of the property associated with this attribute is not supported, then a presentation processor must use the value lrtb.

The tts:writingMode style is illustrated by the following example.

Example Fragment – Writing Mode
<region xml:id="r1">
  <style tts:extent="50px 570px"/>
  <style tts:origin="0px 0px"/>
  <style tts:padding="10px 3px"/>
  <style tts:backgroundColor="black"/>
  <style tts:color="white"/>
  <style tts:writingMode="tbrl"/>
</region>
<region xml:id="r2">
  <style tts:extent="310px 50px"/>
  <style tts:origin="70px 120px"/>
  <style tts:padding="10px 3px"/>
  <style tts:backgroundColor="black"/>
  <style tts:color="white"/>
  <style tts:writingMode="rltb"/>
</region>
...
<p region="r1">
  I sometimes dig for buttered rolls,<br/>
  Or set limed twigs for crabs:
</p>
<p region="r2" tts:direction="rtl" tts:unicodeBidi="bidiOverride">
  I sometimes search the grassy knolls for the wheels of Hansom-cabs.
</p>

Example Rendition – Writing Mode
TTML writingMode style property

Note:

In the second paragraph in the above example that targets region r2, the tts:unicodeBidi and tts:direction properties are set to bidiOverride and rtl, respectively, in order to override the normally left-to-right directionality of characters in the Latin script.

Note:

The semantics of the style property represented by this attribute are based upon that defined by [XSL 1.1], § 7.29.7.

8.2.25 tts:zIndex

The tts:zIndex attribute is used to specify a style property that defines the front-to-back ordering of region areas in the case that they overlap.

This attribute may be specified by any element type that permits use of attributes in the TT Style Namespace; however, this attribute applies as a style property only to those element types indicated in the following table.

Values: auto | <integer>
Initial:auto
Applies to: region
Inherited:no
Percentages:N/A
Animatable:discrete

If two areas are associated with the same Z-index value, then, if those areas overlap in space, the area(s) generated by lexically subsequent elements must be rendered over area(s) generated by lexically prior elements, where lexical order is defined as the postorder traversal of a Document Instance.

The tt element is considered to establish the root of the stacking context, as defined by [XSL 1.1], § 7.30.18.

If a computed value of the property associated with this attribute is not supported, then a presentation processor must use the closest supported value.

Note:

In this context, the phrase closest supported value means the value for which the Euclidean distance between the computed z-index and the supported z-index is minimized. If there are multiple closest supported values equally distant from the computed value, then the value least distant from 0, i.e., closest to the base stack level of the current stacking context, is used.

The tts:zIndex style is illustrated by the following example.

Example Fragment – Z Index
<region xml:id="r1">
  <style tts:origin="0px 0px"/>
  <style tts:extent="400px 100px"/>
  <style tts:padding="5px"/>
  <style tts:backgroundColor="black"/>
  <style tts:color="white"/>
  <style tts:zIndex="0"/>
</region>
<region xml:id="r2">
  <style tts:origin="100px 60px"/>
  <style tts:extent="400px 100px"/>
  <style tts:padding="5px"/>
  <style tts:backgroundColor="red"/>
  <style tts:color="white"/>
  <style tts:textAlign="end"/>
  <style tts:zIndex="1"/>
</region>
<region xml:id="r3">
  <style tts:origin="0px 120px"/>
  <style tts:extent="400px 100px"/>
  <style tts:padding="5px"/>
  <style tts:backgroundColor="black"/>
  <style tts:color="white"/>
  <style tts:zIndex="2"/>
</region>
<region xml:id="r4">
  <style tts:origin="100px 180px"/>
  <style tts:extent="400px 100px"/>
  <style tts:padding="5px"/>
  <style tts:backgroundColor="red"/>
  <style tts:color="white"/>
  <style tts:textAlign="end"/>
  <style tts:zIndex="3"/>
</region>
...
<p region="r1">
  I passed by his garden, and marked, with one eye,<br/>
  How the Owl and the Panther were sharing a pie.
</p>
<p region="r2">
  The Panther took pie-crust, and gravy, and meat,<br/>
  While the Owl had the dish as its share of the treat.
</p>
<p region="r3">
  When the pie was all finished, the Owl, as a boon,<br/>
  Was kindly permitted to pocket the spoon:
</p>
<p region="r4">
  While the Panther received knife and fork<br/>
  with a growl,<br/>
  And concluded the banquet by...
</p>

Example Rendition – Z Index
TTML zIndex style property

Note:

The semantics of the style property represented by this attribute are based upon that defined by [XSL 1.1], § 7.30.18.

8.3 Style Value Expressions

Style property values include the use of the following expressions:

In the syntax representations defined in this section, no linear whitespace (LWSP) is implied or permitted between tokens unless explicitly specified.

8.3.1 <alpha>

An <alpha> expression is used to express an opacity value, where 0 means fully transparent and 1 means fully opaque.

Syntax Representation – <alpha>
<alpha>
  : float

In the above syntax representation, the syntactic element float must adhere to the lexical representation defined by [XML Schema Part 2] § 3.2.4.1. If the value represented is less than 0.0, then it must be interpreted as equal to 0.0; similarly, if the value represented is greater than 1.0, then it must be interpreted as 1.0. The value NaN must be interpreted as 0.0.

A specified value for <alpha> should not be NaN, less than 0, or greater than 1.

If a presentation processor does not support a specific, valid opacity value, then it must interpret it as being equal to the closest supported value.

Note:

In this context, the phrase closest supported value means the value for which the Euclidean distance between the computed opacity and the supported opacity is minimized. If there are multiple closest supported values equally distant from the computed value, then the value most distant from 0, i.e., the greatest opacity, is used.

8.3.2 <color>

A <color> expression is used to specify a named color, exact RGB color triple, or exact RGBA color tuple, where the alpha component, if expressed, is maximum (255) at 100% opacity and minimum (0) at 0% opacity, and where the applicable color space is defined by [SRGB].

Syntax Representation – <color>
<color>
  : "#" rrggbb
  | "#" rrggbbaa
  | "rgb(" r-value "," g-value "," b-value ")"
  | "rgba(" r-value "," g-value "," b-value "," a-value ")"
  | <namedColor>

rrggbb
  :  <hexDigit>{6}

rrggbbaa
  :  <hexDigit>{8}

r-value | g-value | b-value | a-value
  : component-value

component-value
  : non-negative-integer                    // valid range: [0,255]

non-negative-integer
  : <digit>+

Note:

While permitted, the use of linear whitespace (LWSP) around the comma delimiters in <color> expressions is not recommended. The rationale for this recommendation is that some existing processors may not be tolerant of this usage.

When expressing RGB component values, these values are considered to not be premultiplied by alpha.

For the purpose of performing presentation processing such that non-opaque or non-transparent alpha or opacity values apply, then the semantics of compositing functions are defined with respect to the use of the [SRGB] color space for both inputs and outputs of the composition function.

Note:

The use of [SRGB] for the stated semantics of composition is not meant to prevent an actual processor from using some other color space either for internal or external purposes. For example, a presentation processor may ultimately convert the SRGB values used here to the YUV color space for rendition on a television device.

If a presentation processor does not support a specific, valid color or alpha value, then it must interpret it as being equal to the closest supported value.

Note:

In this context, the phrase closest supported value means the value for which the Euclidean distance between the computed color or alpha and the supported color or alpha in the RGB color space is minimized. If there are multiple closest supported values equally distant from the computed value, then the value least distant from opaque black rgba(0,0,0,255), i.e., the closest to opaque black, is used.

8.3.3 <digit>

A <digit> is used to express integers and other types of numbers or tokens.

Syntax Representation – <digit>
<digit>
  : "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"

8.3.4 <duration>

This section is non-normative.

Note:

The information from this section has been removed due to lack of any normative use within this specification. This section is retained in its empty form in order to prevent section renumbering.

8.3.5 <familyName>

A <familyName> expression specifies a font family name.

Syntax Representation – <familyName>
<familyName>
  : unquoted-string
  | quoted-string

unquoted-string
  : identifier ( lwsp identifier )*

lwsp
  : ( ' ' | '\t' | '\n' | '\r' )+

identifier
  : [-]? identifier-start identifier-following*

identifier-start
  : [_a-zA-Z]
  | non-ascii-or-c1
  | escape

identifier-following
  : [_a-zA-Z0-9-]
  | non-ascii-or-c1
  | escape

non-ascii-or-c1
  : [^\0-\237]

escape
  : '\\' char

quoted-string
  : double-quoted-string
  | single-quoted-string

double-quoted-string
  : '"' ( [^"\\] | escape )+ '"'

single-quoted-string
  : "'" ( [^'\\] | escape )+ "'"

In addition to adhering to the syntax rules specified above, the following semantic rules apply:

  • the semantic value of a <familyName> expression is the semantic value of its unquoted-string or quoted-string non-terminal, according to whichever applies;

  • the semantic value of an unquoted-string non-terminal is a pair <quoted, content>, where quoted is a boolean false, and where content is the result of appending the value of each identifier non-terminal, in lexical order, where the value of each identifier is preceded by a single SPACE (U+0020) character if it is not the first identifier;

  • the semantic value of a quoted-string non-terminal is a pair <quoted, content>, where quoted is a boolean true, and where content is the unquoted content of the quoted string, i.e., the sequence of characters between the delimiting quotes.

  • the semantic value of an escape non-terminal is the value of the escaped char;

  • a <familyName> that takes the form of an unquoted-string that contains an identifier that starts with two - HYPHEN-MINUS (U+002D) characters must be considered to be invalid;

  • a <familyName> that takes the form of an unquoted-string that contains a single identifier that matches (by case sensitive comparison) a <genericFamilyName> must be interpreted as that <genericFamilyName>;

  • a <familyName> that takes the form of a quoted-string whose content (unquoted value) matches (by case sensitive comparison) a <genericFamilyName> must not be interpreted as that <genericFamilyName>, but as the actual name of a non-generic font family.

Note:

The syntactic element char is to be interpreted according to the Char production defined by [XML 1.0] §2.2.

Note:

The {unicode} escape mechanism defined by [CSS2] §4.1.1 is not supported by this syntax; rather, authors are expected to either (1) directly encode the character using the document encoding or (2) use an XML character reference according to [XML 1.0] §4.1. When a syntactically significant character needs to be used without its normal syntactic interpretation, it may be be escaped using the backslash (reverse solidus) escape non-terminal specified above.

When using the backslash (reverse solidus) escape non-terminal, the above syntax does not place any restriction on what character may be escaped, e.g., \\[\n\r\f0-9a-f] are permitted. If one of these latter escapes appears in a <familyName> expression, then it will need to be converted to a {unicode} escape if it is to be used with a standard XSL-FO or CSS parser. In particular, a backslash followed by a newline is ignored by CSS, while it is not ignored by the above syntax. Such an unignored escaped newline would need to be represented using an equivalent {unicode} escape, such as \a, to order to express in CSS.

8.3.6 <genericFamilyName>

A <genericFamilyName> expression specifies a font family using a general token that indicates a class of font families.

The resolution of a generic family name to a concrete font instance is considered to be implementation dependent, both in the case of content authoring and content interpretation.

Syntax Representation – <genericFamilyName>
<genericFamilyName>
  : "default"
  | "monospace"
  | "sansSerif"
  | "serif"
  | "monospaceSansSerif"
  | "monospaceSerif"
  | "proportionalSansSerif"
  | "proportionalSerif"

The mapping between a generic (font) family name and an actual font is not determined by this specification; however, the distinction of monospace versus proportional and serif versus sans-serif should be maintained if possible when performing presentation.

If a generic (font) family name of monospace is specified, then it may be interpreted as equivalent to either monospaceSansSerif or monospaceSerif. The generic family names sansSerif and serif are to be interpreted as equivalent to proportionalSansSerif and proportionalSerif, respectively.

If the generic family name default is specified (or implied by an initial value), then its typographic characteristics are considered to be implementation dependent; however, it is recommended that this default font family be mapped to a monospaced, sans-serif font.

8.3.7 <hexDigit>

A <hexDigit> is used to express integers and other types of numbers or tokens that employ base 16 arithmetic.

For the purpose of parsing, a distinction must not be made between lower and upper case.

Syntax Representation – <hexDigit>
<hexDigit>
  : <digit>
  | "a" | "b" | "c" | "d" | "e" | "f"
  | "A" | "B" | "C" | "D" | "E" | "F"

8.3.8 <integer>

An <integer> expression is used to express an arbitrary, signed integral value.

Syntax Representation – <integer>
<integer>
  : ( "+" | "-" )? <digit>+

8.3.9 <length>

A <length> expression is used to express either a coordinate component of point in a cartesian space or a distance between two points in a cartesian space.

Syntax Representation – <length>
<length>
  : scalar
  | percentage

scalar
  : number units

percentage
  : number "%"

sign
  : "+" | "-"

number
  : sign? non-negative-number

non-negative-number
  : non-negative-integer
  | non-negative-real

non-negative-integer
  : <digit>+

non-negative-real
  : <digit>* "." <digit>+

units
  : "px"
  | "em"
  | "c"                                     // abbreviation of "cell"

It is an error to omit the units component of a scalar length value.

The semantics of the unit of measure px (pixel) are as defined by [XSL 1.1], § 5.9.13.

When specified relative to a font whose size is expressed as a single length measure or as two length measures of equal length, the unit of measure em is considered to be identical to that defined by [XSL 1.1], § 5.9.13; however, when specified relative to a font whose size is expressed as two length measures of non-equal lengths, then one em is equal to the inline progression dimension of the anamorphically scaled font when used to specify lengths in the inline progression direction and equal to the block progression dimension of the scaled font when used to specify lengths in the block progression direction.

The semantics of the unit of measure c (cell) are defined by the parameter 6.2.1 ttp:cellResolution.

8.3.10 <namedColor>

A <namedColor> is used to express an RGBA color with a convenient name, and where the applicable color space is defined by [SRGB].

For the purpose of parsing, a distinction must not be made between lower and upper case.

Syntax Representation – <namedColor>
<namedColor>
  : "transparent"                           // #00000000
  | "black"                                 // #000000ff
  | "silver"                                // #c0c0c0ff
  | "gray"                                  // #808080ff
  | "white"                                 // #ffffffff
  | "maroon"                                // #800000ff
  | "red"                                   // #ff0000ff
  | "purple"                                // #800080ff
  | "fuchsia"                               // #ff00ffff
  | "magenta"                               // #ff00ffff (= fuchsia)
  | "green"                                 // #008000ff
  | "lime"                                  // #00ff00ff
  | "olive"                                 // #808000ff
  | "yellow"                                // #ffff00ff
  | "navy"                                  // #000080ff
  | "blue"                                  // #0000ffff
  | "teal"                                  // #008080ff
  | "aqua"                                  // #00ffffff
  | "cyan"                                  // #00ffffff (= aqua)

Note:

Except for transparent, the set of named colors specified above constitutes a proper subset of the set of named colors specified by [SVG 1.1], § 4.2.

8.3.11 <quotedString>

This section is non-normative.

Note:

The information from this section has been incorporated into 8.3.5 <familyName>. This section is retained in its empty form in order to prevent section renumbering.

8.3.12 <string>

This section is non-normative.

Note:

The information from this section has been incorporated into 8.3.5 <familyName>. This section is retained in its empty form in order to prevent section renumbering.

8.4 Style Resolution

This section defines the semantics of style resolution in terms of a standard processing model as follows:

Any implementation of this model is permitted provided that the externally observable results are consistent with the results produced by this model.

Note:

The semantics of style resolution employed here are based upon [XSL 1.1], § 5.

8.4.1 Style Association

Style association is a sub-process of 8.4.4 Style Resolution Processing used to determine the specified style set of each content and layout element.

Style matter may be associated with content and layout matter in a number of ways:

In addition to the above, style matter may be associated with layout matter using:

8.4.1.1 Inline Styling

Style properties may be expressed in an inline manner by direct specification of an attribute from the TT Style Namespace on the affected element. When expressed in this manner, the association of style information is referred to as inline styling.

Style properties associated by inline styling are afforded a higher priority than all other forms of style association.

Example – Inline Styling
<p tts:color="white">White 1 <span tts:color="yellow">Yellow</span> White 2</p>

Note:

In the above example, the two text fragments "White 1 " and " White 2", which are interpreted as anonymous spans, are not associated with a color style property; rather, they inherit their color style from their parent p element as described in 8.4.2.1 Content Style Inheritance below.

8.4.1.2 Referential Styling

Style properties may be expressed in an out-of-line manner and referenced by the affected element using the style attribute. When expressed in this manner, the association of style information is referred to as referential styling.

If a style attribute specifies multiple references, then those references are evaluated in the specified order, and that order applies to resolution of the value of a style property in the case that it is specified along multiple reference paths.

The use of referential styling is restricted to making reference to style element descendants of a styling element. It is considered an error to reference a style element that is a descendant of a layout element.

Note:

The use of referential styling encourages the reuse of style specifications while sacrificing locality of reference.

Note:

A single Content element may be associated with style properties by a hybrid mixture of inline and referential styling, in which case inline styling is given priority as described above by 8.4.1.1 Inline Styling.

Example – Referential Styling
<style xml:id="s1" tts:color="white"/>
<style xml:id="s2" tts:color="yellow"/>
...
<p style="s1">White 1 <span style="s2">Yellow</span> White 2</p>

Note:

In the above example, the two text fragments "White 1 " and " White 2", which are interpreted as anonymous spans, are not associated with a color style property; rather, they inherit their color style from their parent p element as described in 8.4.2.1 Content Style Inheritance below.

8.4.1.3 Chained Referential Styling

Style properties may be expressed in an out-of-line manner and may themselves reference other out-of-line style properties, thus creating a chain of references starting at the affected element. When expressed in this manner, the association of style information is referred to as chained referential styling.

A loop in a sequence of chained style references must be considered an error.

The use of referential styling is restricted to making reference to style element descendants of a styling element. It is considered an error to reference a style element that is a descendant of a layout element.

Note:

The use of chained referential styling encourages the grouping of style specifications into general and specific sets, which further aids in style specification reuse.

Note:

A single Content element may be associated with style properties by a hybrid mixture of inline, referential styling, and chained referential styling, in which case inline styling is given priority as described above by 8.4.1.1 Inline Styling.

Example – Chained Referential Styling
<style xml:id="s1" tts:color="white" tts:fontFamily="monospaceSerif"/>
<style xml:id="s2" style="s1" tts:color="yellow"/>
...
<p style="s1">White Monospace</p>
<p style="s2">Yellow Monospace</p>

Note:

In the above example, the text of the second paragraph is yellow, since tts:color='yellow' effectively overwrites (is merged over) the tts:color='white' that style s2 obtains by a reference to style s1.

8.4.1.4 Nested Styling

Style properties may be expressed in a nested manner by direct specification of one or more style element children of the affected element. When expressed in this manner, the association of style information is referred to as nested styling.

Style properties associated by nested styling are afforded a lower priority than inline styling but with higher priority than referential styling.

Example – Nested Styling
<region xml:id="r1">
  <style tts:extent="128px 66px"/>
  <style tts:origin="0px 0px"/>
  <style tts:displayAlign="center"/>
</region>

Note:

In this version of this specification, nested styling applies only to the region element.

8.4.2 Style Inheritance

Style inheritance is a sub-process of 8.4.4 Style Resolution Processing used to determine the specified style set of each content and layout element.

Styles are further propagated to content matter using:

For the purpose of determining inherited styles, the element hierarchy of an intermediate synchronic document form of a Document Instance must be used, where such intermediate forms are defined by 9.3.3 Intermediate Synchronic Document Construction.

Note:

The intermediate synchronic document form is utilized rather than the original form in order to facilitate region inheritance processing.

8.4.2.1 Content Style Inheritance

Style properties are inherited from ancestor Content elements within an intermediate synchronic document if a style property is not associated with a Content element (or an anonymous span) and the style property is designated as inheritable.

Note:

The tt element is not a Content element; consequently, the body element is the outermost element from which content style inheritance occurs.

If a style property is determined to require inheritance, then the inherited value must be the value of the same named style property in the computed style set of the element's immediate ancestor element within the applicable intermediate synchronic document.

Example – Content Style Inheritance
<p tts:fontFamily="monospaceSansSerif">
  <span tts:color="yellow">Yellow Monospace</span>
</p>

Note:

In the above example, the span element that encloses the character items Yellow Monospace is not associated with a tts:fontFamily style property and this property is inheritable; therefore, the value of the tts:fontFamily style is inherited from the computed style set of the ancestor p element, and is added to the specified style set of the span element.

8.4.2.2 Region Style Inheritance

Style properties are inherited from a region element in the following case:

  1. if a style property P is not associated with a Content element or an anonymous span E and the style property is designated as inheritable, and

  2. if that style property P is in the computed style set of region R, and

  3. if that element E is flowed into (presented within) region R.

Example – Region Style Inheritance
<region xml:id="r1">
  <style tts:color="yellow"/>
  <style tts:fontFamily="monospaceSerif"/>
</region>
...
<p region="r1">Yellow Monospace</p>

Note:

In the above example, the anonymous span that encloses the character items Yellow Monospace effectively inherits the tts:color and tts:fontFamily styles specified on the region element into which the p element is flowed (presented).

8.4.3 Style Resolution Value Categories

During style resolution, layout, and presentation processing, three categories of style property values are distinguished as follows:

8.4.3.1 Specified Values

Values of style properties that are associated with or inherited by an element or anonymous span are referred to as specified values. The set of all specified style properties of a given element is referred to as the specified style set of that element.

8.4.3.2 Computed Values

When style properties are specified using relative value expressions, such as a named color, a relative unit (e.g., cell), or a percentage, then they need to be further resolved into absolute units, such as an RGB triple, pixels, etc.

During the style resolution process, all specified style values are reinterpreted (or recalculated) in absolute terms, and then recorded as computed values. The set of all computed style properties of a given element is referred to as the computed style set of that element.

When a style value is inherited, either explicitly or implicitly, it is the computed value of the style that is inherited from an ancestor element. This is required since the resolution of certain relative units, such as percentage, require evaluating the expression in the immediate (local) context of reference, and not in a distant (remote) context of reference where the related (resolving) expression is not available.

8.4.3.3 Actual Values

During the actual presentation process, other transformations occur that map some value expressions to concrete, physical values. For example, the colors of computed style values are further subjected to closest color approximation and gamma correction during the display process. In addition, length value expressions that use pixels in computed style values are considered to express logical rather than physical (device) pixels. Consequently, these logical pixels are subject to being further transformed or mapped to physical (device) pixels during presentation.

The final values that result from the logical to device mapping process are referred to as actual values. The set of all actual style properties of a given element is referred to as the actual style set of that element.

Note:

More than one set of actual values may be produced during the process of presentation. For example, a TTML presentation processor device may output an RGBA component video signal which is then further transformed by an NTSC or PAL television to produce a final image. In this case, both color and dimensions may further be modified prior to presentation.

Note:

In general, a TTML presentation processor will not have access to actual style set values; as a consequence, no further use or reference to actual values is made below when formally describing the style resolution process.

8.4.4 Style Resolution Processing

The process of style resolution is defined herein as the procedure (and results thereof) for resolving (determining) the computed values of all style properties that apply to content and layout elements:

The process described here forms an integral sub-process of 9.3 Region Layout and Presentation.

8.4.4.1 Conceptual Definitions

For the purpose of interpreting the style resolution processing model specified below, the following conceptual definitions apply:

[style property]

a style property, P, is considered to consist of a tuple [name, value], where the name of the property is a tuple [namespace value, unqualified name] and the value of the property is a tuple [category, type, value expression]

Example – conceptual style property
[
  ["http://www.w3.org/ns/ttml#styling", "color"],
  ["specified", color, "red"]
]

[style (property) set]

a style (property) set consists of an unordered collection of style properties, where no two style properties within the set have an identical name, where by "identical name" is meant equality of namespace value of name tuple and unqualified name of name tuple;

in a specified style (property) set, the category of each style property is "specified"; a specified style (property) set of an element E is referred to as SSS(E);

Example – conceptual (specified) style (property) set
{
  [
    ["http://www.w3.org/ns/ttml#styling", "backgroundColor"],
    ["specified", color, 0x00FF00 ]
  ],
  [
    ["http://www.w3.org/ns/ttml#styling", "color"],
    ["specified", color, "red" ]
  ],
  [
    ["http://www.w3.org/ns/ttml#styling", "fontSize"],
    ["specified", length, "1c" ]
  ],
  [
    ["http://www.w3.org/ns/ttml#styling", "lineHeight"],
    ["specified", length, "117%" ]
  ]
}

in a computed style (property) set, the category of each style property is either "specified" or "computed"; a computed style (property) set of an element E is referred to as CSS(E);

Example – conceptual (computed) style (property) set
{
  [
    ["http://www.w3.org/ns/ttml#styling", "backgroundColor"],
    ["specified", color, 0x00FF00 ]
  ],
  [
    ["http://www.w3.org/ns/ttml#styling", "color"],
    ["computed", color, 0xFF0000 ]
  ],
  [
    ["http://www.w3.org/ns/ttml#styling", "fontSize"],
    ["computed", length, "24px" ]
  ],
  [
    ["http://www.w3.org/ns/ttml#styling", "lineHeight"],
    ["computed", length, "28px" ]
  ]
}

[style (property) merging]

a style property Pnew is merged into a style (property) set, SS, as follows: if a style property Pold is already present in SS where the name of Pnew is identical to the name of Pold, then replace Pold in SS with Pnew; otherwise, add Pnew to SS;

[style (property) set merging]

a style (property) set SSnew is merged into an existing style (property) set SSold as follows: for each style property Pnew in SSnew, merge Pnew into SSold;

8.4.4.2 Specified Style Set Processing

The specified style set SSS of an element or anonymous span E, SSS(E), is determined according to the following ordered rules:

  1. [initialization] initialize the specified style set SSS of E to the empty set;

  2. [referential and chained referential styling] for each style element SREF referenced by a style attribute specified on E, and in the order specified in the style attribute, then, if SREF is a descendant of a styling element, merge the specified style set of SREF, SSS(SREF), into the specified style set of E, SSS(E);

  3. [nested styling] for each nested style element child SNEST of E, and in the specified order of child elements, merge the specified style set of SNEST, SSS(SNEST), into the specified style set of E, SSS(E);

  4. [inline styling] for each style property P expressed as a specified styling attribute of E, merge P into the specified style set of E, SSS(E);

  5. [animation styling] for each style property P expressed as a specified styling attribute of an immediate animation (set) element child of element E, merge P into the specified style set of E, SSS(E);

  6. [implicit inheritance] if the element type of E is not the styling element type style, then for each style property P in the set of style properties defined above in 8.2 Styling Attribute Vocabulary, perform the following ordered sub-steps:

    1. if P is present in the specified style set of E, SSS(E), then continue to the next style property;

    2. if P is inheritable and E is a region element, or if P is not inheritable and applies to E, then set P′ to the initial value of property P if such an initial value is defined, where the initial value of a property is determined according to the specific property definition found above in 8.2 Styling Attribute Vocabulary;

    3. if P is inheritable and the element type of E is a Content element type or anonymous span, then set P′ to the result of looking up the value of P in the computed style set of the immediate ancestor element of E, i.e., CSS(PARENT(E));

    4. if the value of P′ is not undefined, then merge P′ into the specified style set of E, SSS(E).

8.4.4.3 Computed Style Set Processing

The computed style set CSS of an element or anonymous span E, CSS(E), is determined according to the following ordered rules:

  1. [resolve specified styles] determine (obtain) the specified style set SSS of E, namely, SSS(E), in accordance with 8.4.4.2 Specified Style Set Processing;

  2. [initialization] initialize CSS(E) to a (deep) copy of SSS(E);

  3. [filter] if E is a style element, then return CSS(E) as the resulting computed style set without further resolution; otherwise, continue with the next rule;

  4. [relative value resolution] for each style property P in CSS(E), where the value type of P is relative, perform the following ordered sub-steps:

    1. replace the relative value of P with an equivalent, non-relative (computed) value;

    2. set the category of P to "computed";

Note:

As a result of the filtering rule above, the computed style set of a style element includes only specified values, in which case relative value expressions remain relative; consequently, the resolution of relative value expressions (that may be assigned by means of referential style association) always takes place in the context of a layout or Content element which has a presentation context, and not in the non-presentation, declaration context of a referentiable style element.

Note:

See individual style properties for additional inheritance semantics, if any.

8.4.4.4 Style Resolution Process

The top-level style resolution process is defined as follows: using a preorder traversal of each element and anonymous span, E, of an intermediate synchronic document, DOCinter, perform the following ordered sub-steps:

  1. [filter] if the element type of E is not the styling element type style, is not the layout element type region, and is not one of the Content element types body, div, p, span, br, or anonymous span, then continue to the next element in the preorder traversal;

  2. [resolve computed styles] determine (obtain) the computed style set CSS of E, namely, CSS(E), in accordance with 8.4.4.3 Computed Style Set Processing.

9 Layout

This section specifies the layout matter of the core vocabulary catalog, where layout is to be understood as a separable layer of information that applies to content and that denotes authorial intentions about the presentation of that content.

Note:

The two layers of layout and style matter are considered to be independently separable. Layout matter specifies one or more spaces or areas into which content is intended to be presented, while style matter specifies the manner in which presentation occurs within the layout.

In certain cases, a content author may choose to embed (inline) style matter directly into layout or content matter. In such cases, an alternative exists – use of referential styling – in which the style matter is not embedded (inlined).

9.1 Layout Element Vocabulary

The following elements specify the structure and principal layout aspects of a Document Instance:

9.1.1 layout

The layout element is a container element used to group layout matter, including metadata that applies to layout matter.

The layout element accepts as its children zero or more elements in the Metadata.class element group, followed by zero or more region elements.

XML Representation – Element Information Item: layout
<layout
  xml:id = ID
  xml:lang = string
  xml:space = (default|preserve)
  {any attribute not in default or any TT namespace}>
  Content: Metadata.class*, region*
</layout>

To the extent that time semantics apply to the content of the layout element, the implied time interval of this element is defined to be coterminous with the Root Temporal Extent.

9.1.2 region

The region element is used to define a rectangular space or area into which content is to be flowed for the purpose of presentation.

Note:

The rectangular area of a region is explicitly not constrained to be contained within the Root Container Region. In particular, the origin components of a region may be negative, and the extent (width and height) components of a region may be greater than the width and height of the Root Container Region. Whether a presentation processor clips such a region to the Root Container Region is implementation dependent, and not prescribed by this specification.

In addition, and in accordance with 8.4.2.2 Region Style Inheritance, the region element may be used to specify inheritable style properties to be inherited by content that is flowed into it.

The region element accepts as its children zero or more elements in the Metadata.class element group, followed by zero or more elements in the Animation.class element group, followed by zero or more style elements.

Any metadata specified by children in the Metadata.class element group applies semantically to the region element and its descendants as a whole. Any animation elements specified by children in the Animation.class element group apply semantically to the region element. Any style child element must be considered a local style definition that applies only to the containing region element, i.e., does not apply for resolving referential styling (but does apply for region style inheritance).

XML Representation – Element Information Item: region
<region
  begin = <timeExpression>
  dur = <timeExpression>
  end = <timeExpression>
  style = IDREFS
  timeContainer = (par|seq)
  ttm:role = string
  xml:id = ID
  xml:lang = string
  xml:space = (default|preserve)
  {any attribute in TT Style namespace}
  {any attribute not in default or any TT namespace}>
  Content: Metadata.class*, Animation.class*, style*
</region>

If begin and (or) end attributes are specified on a region element, then they specify the beginning and (or) ending points of a time interval during which the region is eligible for activation and with respect to which animation child elements of the region are timed. If specified, these begin and end points are relative to the time interval of the nearest ancestor element associated with a time interval, irregardless of whether that interval is explicit or implied.

The nearest ancestor element of a region element that is associated with a time interval is the layout element.

If a dur attribute is specified on the region element, then it specifies the simple duration of the region.

For the purpose of determining the semantics of presentation processing, a region that is temporally inactive must not produce any visible marks when presented on a visual medium.

Note:

A region element may be associated with a time interval for two purposes: (1) in order to temporally bound the presentation of the region and its content, and (2) to provide a temporal context in which animations of region styles may be effected.

For example, an author may wish to specify a region that is otherwise empty, but may have a visible background color to be presented starting at some time and continuing over the region's duration. The simple duration of the region serves additionally to scope the presentation effects of content that is targeted to the region. An author may also wish to move a region within the Root Container Region or change a region's background color by means of animation effects. In both of these cases, it is necessary to posit an active time interval for a region.

If no timeContainer attribute is specified on a region element, then it must be interpreted as having parallel time containment semantics.

If a ttm:role attribute is specified on a region element, then it must adhere to the value syntax defined by Syntax Representation – ttm:role, and where the roles identified by this attribute express the semantic roles of the region independently from the semantic roles of any content targeted to (associated with) the region.

9.2 Layout Attribute Vocabulary

This section defines the 9.2.1 region attribute used with Content elements.

9.2.1 region

The region attribute is used to reference a region element which defines a space or area into which a Content element is intended to be flowed.

If specified, the value of a region attribute must adhere to the IDREF data type defined by [XML Schema Part 2], § 3.3.9, and, furthermore, this IDREF must reference a region element which has a layout element as an ancestor.

The region attribute may be specified by an instance of the following element types:

Note:

See 9.3 Region Layout and Presentation below for further information on content flow in a region.

9.3 Region Layout and Presentation

This section defines the semantics of region layout and presentation in terms of a standard processing model as follows:

Any implementation is permitted provided that the externally observable results are consistent with the results produced by this model.

9.3.1 Default Region

If a Document Instance does not specify a region element, then a default region is implied with the following characteristics:

  • the identity of the default region is considered to be anonymous;

  • the extent of the default region is the same as the extent of the Root Container Region;

  • the temporal interval of the default region is the same as the interval defined by the Root Temporal Extent;

Furthermore, if no region element is specified, then the region attribute must not be specified on any Content element in the Document Instance.

If a default region is implied for a given Document Instance, then the body element is implicitly targeted to (associated with) the default region.

When implying a default region, the Document Instance is to be treated as if a region element and its parent layout element were specified in a head element, and a matching region attribute were specified on the body element as shown in the following example:

Example – Implied Default Region
<tt xml:lang="" xmlns="http://www.w3.org/ns/ttml">
  <head>
    <layout>
      <region xml:id="anonymous"/>
    </layout>
  </head>
  <body region="anonymous"/>
</tt>

Note:

In the above example, a default region element and region attribute are implied. In addition, a layout container element is implied for the implied region element.

9.3.2 Anonymous Span Construction

For the purposes of performing presentation processing, anonymous spans are created according to the following [construct anonymous spans] procedure:

[construct anonymous spans]
  1. for each significant text node in a Content element, synthesize an anonymous span to enclose the text node, substituting the new anonymous span for the original text node child in its sibling and parent hierarchy;

  2. for each contiguous sequence of anonymous spans, replace the sequence with a single anonymous span which contains a sequence of text nodes representing the individual text node children of the original sequence of anonymous spans;

  3. for each span element whose child is a single anonymous span, replace the anonymous span with its sequence of child text nodes;

9.3.3 Intermediate Synchronic Document Construction

For the purposes of performing presentation processing, the active time duration of a Document Instance is divided into a sequence of time coordinates where at each time coordinate, some element becomes temporally active or inactive, then, at each such time coordinate, a Document Instance is mapped from its original, source form, DOCsource , to an intermediate synchronic document form, DOCinter , according to the [construct intermediate document] procedure:

[construct intermediate document]
  1. for each temporally active region R, replicate the sub-tree of DOCsource headed by the body element;

  2. evaluating this sub-tree in a postorder traversal, prune elements if any of the following conditions is true:

    1. they are neither Content nor Animation elements; or

    2. they are temporally inactive but not br elements; or

    3. they are empty and neither Animation elements nor br elements; or

    4. they are Content elements and aren't associated with region R according to the [associate region] procedure.

  3. if the pruned sub-tree is non-empty, then reparent it to the R element;

  4. finally, after completing the above steps, prune the original body element from the intermediate document, then prune all region, begin, end, and dur attributes, which are no longer semantically relevant;

Note:

In this section, the term prune, when used in reference to an element, means that the element is to be removed from its parent's children, which, in turn, implies that the descendants of the pruned element will no longer be descendants of the element's parent. When prune is used in reference to an attribute, it means that attribute is to be removed from its associated (owning) element node.

[associate region]

A Content element is associated with a region according to the following ordered rules, where the first rule satisfied is used and remaining rules are skipped:

  1. if the element specifies a region attribute, then the element is associated with the region referenced by that attribute;

  2. if some ancestor of that element specifies a region attribute, then the element is associated with the region referenced by the most immediate ancestor that specifies this attribute;

  3. if the element contains a descendant element that specifies a region attribute, then the element is associated with the region referenced by that attribute;

  4. if a default region was implied (due to the absence of any region element), then the element is associated with the default region;

  5. the element is not associated with any region.

The result of performing the processing described above will be a sequence of N intermediate synchronic Document Instances, DOCinter0DOCinterN−1.

Note:

Where an implementation is able to detect significant similarity between two adjacent synchronic Document Instances, DOCinterN DOCinterN−1, then the implementation can apply processing to make the transition between presenting the two instances as smooth as possible, e.g., as described by [CEA-608-E], § C.3, and [CC-DECODER-REQ].

9.3.4 Synchronic Flow Processing

Subsequent to performing a temporal (synchronic) slice and subsequent remapping of regionally selected content hierarchy, the resulting intermediate synchronic document is subjected to a flow transformation step that produces a rooted flow object tree represented as an XSL FO document instance as defined by [XSL 1.1], and semantically extended by TTML specific style properties that have no XSL FO counterpart.

Note:

In this section, the use of XSL FO is intended to be conceptual only, employed solely for the purpose of defining the normative presentation semantics of TTML. An actual implementation of this algorithm is not required to create or process XSL-FO representations. In particular, it is possible to implement these semantics using alternative presentation models, such as Cascading Style Sheets (CSS).

Each intermediate synchronic document produced by 9.3.3 Intermediate Synchronic Document Construction is mapped to an XSL FO document instance, F, as follows:

  1. perform the [construct anonymous spans] procedure;

  2. resolve styles according to 8.4.4.4 Style Resolution Process;

  3. map the tt element to an fo:root element, populated initially with an fo:layout-master-set element that contains a valid fo:simple-page-master that, in turn, contains an fo:region-body child, where the extent of the Root Container Region expressed on the tt element is mapped to page-width and page-height attributes on the fo:simple-page-master element;

  4. map the layout element to an fo:page-sequence element and a child fo:flow element that reference the page master and page region defined by the simple page master produced above;

  5. map each non-empty region element to an fo:block-container element with an absolute-position attribute with value absolute, with top, left, bottom, and right attributes that express a rectangle equivalent to the region's origin, extent (including padding), and with a line-stacking-strategy attribute with value line-height;

    Note:

    The region's extent corresponds with the allocation rectangle of the block area generated by the fo:block-container.

  6. for each body, div, and p element that is not associated with a tts:display style property with the value none, map the element to a distinct fo:block element, populating the style properties of fo:block by using the computed style set associated with each original TTML Content element;

  7. for the resulting fo:block formatting object produced in the previous step that corresponds to the body element, perform the following ordered sub-steps:

    1. if the display-align style property of this fo:block has the value center or after, then synthesize and insert as the first child of this fo:block an empty fo:block with the following attributes: space-after.optimum, space-after.maximum, and space-after.conditionality, where the value of the former two attributes is the height or width of the containing fo:block-container element, whichever of these is designated as the block progression dimension, and where the value of the last is retain;

    2. if the display-align style property of this fo:block has the value center or before, then synthesize and insert as the last child of this fo:block an empty fo:block with the following attributes: space-after.optimum, space-after.maximum, and space-after.conditionality, where the value of the former two attributes is the height or width of the containing fo:block-container element, whichever of these is designated as the block progression dimension, and where the value of the last is retain;

  8. for each span element that is not associated with a tts:display style property with the value none and for each anonymous span that is a child of a p or span element, map the element or sequence of character items to a distinct fo:inline element, populating the style properties of fo:inline by using the computed style set associated with each original TTML Content element or anonymous span;

  9. for each br element that is not associated with a tts:display style property with the value none, map the element to a distinct fo:character element having the following properties:

    • character="&#x000A;"

    • suppress-at-line-break="retain"

  10. for each TTML style property attribute in some computed style set that has no counterpart in [XSL 1.1], map that attribute directly through to the relevant formatting object produced by the input TTML Content element to which the style property applies;

  11. optionally, synthesize a unique id attribute on each resulting formatting object element that relates that element to the input element that resulted in that formatting object element;

For each resulting document instance F, if processing requires presentation on a visual medium, then apply formatting and rendering semantics consistent with that prescribed by [XSL 1.1].

Note:

In an XSL FO area tree produced by formatting F using an [XSL 1.1] formatting processor, the page-viewport-area, which is generated by fo:page-sequence element by reference to the sole generated fo:simple-page-master element, would correspond to the Root Container Region defined above in 2 Definitions.

Note:

When mapping a region element to fo:block-container, it may be necessary to use a negative offset as a value for one or more of the top, left, bottom, and right XSL-FO properties in case the region extends outside of its containing block.

Note:

Due to the possible presence of TTML style properties or style property values in a given Document Instance for which there is no [XSL 1.1] counterpart, Implementors should recognize that it is the layout model of [XSL 1.1] that is being referenced by this specification, not the requirement to use a compliant [XSL 1.1] formatting processor, since such would not necessarily be sufficient to satisfy the full presentation semantics defined by this specification, and would contain a large number of features not needed to implement the presentation semantics of TTML.

Note:

The purpose of inserting additional, collapsible space in the block progression dimension of the fo:block that corresponds with the body element is to ensure that the before and after edges of this fo:block are coincident with the before and after edges of the fo:block-container that corresponds to the containing region, while simultaneously taking into account the needs to satisfy alignment in the block progression dimension. For example, this assures that the background color associated with the body element, if not transparent, will fill the containing region wholly.

9.3.5 Elaborated Example (Informative)

An example of the processing steps described above is elaborated below, starting with Example – Sample Source Document.

Example – Sample Source Document
<tt tts:extent="640px 480px" xml:lang="en"
  xmlns="http://www.w3.org/ns/ttml"
  xmlns:tts="http://www.w3.org/ns/ttml#styling">
  <head>
    <layout>
      <region xml:id="r1">
        <style tts:origin="10px 100px"/>
        <style tts:extent="620px 96px"/>
        <style tts:fontSize="40px"/>
        <style tts:fontWeight="bold"/>
        <style tts:backgroundColor="black"/>
        <style tts:color="red"/>
        <style tts:textAlign="center"/>
        <style tts:displayAlign="center"/>
      </region>
      <region xml:id="r2">
        <style tts:origin="10px 300px"/>
        <style tts:extent="620px 96px"/>
        <style tts:fontSize="40px"/>
        <style tts:fontWeight="bold"/>
        <style tts:backgroundColor="black"/>
        <style tts:color="yellow"/>
        <style tts:textAlign="center"/>
        <style tts:displayAlign="center"/>
      </region>
    </layout>
  </head>
  <body xml:id="b1">
    <div xml:id="d1" begin="0s" dur="2s">
      <p xml:id="p1" region="r1">Text 1</p>
      <p xml:id="p2" region="r2">Text 2</p>
    </div>
    <div xml:id="d2" begin="1s" dur="2s">
      <p xml:id="p3" region="r2">Text 3</p>
      <p xml:id="p4" region="r1">Text 4</p>
    </div>
  </body>
</tt>

In the above document, the content hierarchy consists of two divisions, each containing two paragraphs. This content is targeted (associated with) one of two non-overlapping regions that are styled identically except for their position and their foreground colors, the latter of which is inherited by and applies to the (and, in this case, anonymous) spans reparented into the regions.

The following, first intermediate document shows the synchronic state for time interval [0,1), during which time only division d1 is temporally active, and where paragraphs p1 and p2 (and their ancestors) are associated with regions r1 and r2, respectively.

Note:

The intermediate documents shown below are not valid Document Instances, but rather, are representations of possible internal processing states used for didactic purposes.

Example – Intermediate Document – [0s,1s)
<tt tts:extent="640px 480px" xml:lang="en"
  xmlns="http://www.w3.org/ns/ttml"
  xmlns:tts="http://www.w3.org/ns/ttml#styling">
  <head>
    <layout>
      <region xml:id="r1">
        <style tts:origin="10px 100px"/>
        <style tts:extent="620px 96px"/>
        <style tts:fontSize="40px"/>
        <style tts:fontWeight="bold"/>
        <style tts:backgroundColor="black"/>
        <style tts:color="red"/>
        <style tts:textAlign="center"/>
        <style tts:displayAlign="center"/>
        <body xml:id="b1-1">
          <div xml:id="d1-1">
            <p xml:id="p1">Text 1</p>
          </div>
        </body>
      </region>
      <region xml:id="r2">
        <style tts:origin="10px 300px"/>
        <style tts:extent="620px 96px"/>
        <style tts:fontSize="40px"/>
        <style tts:fontWeight="bold"/>
        <style tts:backgroundColor="black"/>
        <style tts:color="yellow"/>
        <style tts:textAlign="center"/>
        <style tts:displayAlign="center"/>
        <body xml:id="b1-2">
          <div xml:id="d1-2">
            <p xml:id="p2">Text 2</p>
          </div>
        </body>
      </region>
    </layout>
  </head>
</tt>

An XSL FO document instance that would yield rendering consistent with TTML, and which may be produced by performing flow processing upon the first intermediate document is illustrated below.

Example – XSL FO Document – [0s,1s)
<fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format">
  <fo:layout-master-set>
    <fo:simple-page-master master-name="m1"
      page-width="640px" page-height="480px">
      <fo:region-body/>
    </fo:simple-page-master>
  </fo:layout-master-set>
  <fo:page-sequence master-reference="m1">
    <fo:flow flow-name="xsl-region-body">
      <!-- region (r1) -->
      <fo:block-container id="r1" absolute-position="absolute"
        left="10px" top="100px" width="620px" height="96px"
        background-color="black" display-align="center">
        <!-- body (b1) -->
        <fo:block id="b1-1">
          <!-- body's space (before) filler -->
          <fo:block
            space-after.optimum="96px"
            space-after.maximum="96px"
            space-after.conditionality="retain"/>
          <!-- div (d1) -->
          <fo:block id="d1-1">
            <!-- p (p1) -->
            <fo:block id="p1" text-align="center">
              <fo:inline font-size="40px" font-weight="bold"
              color="red">Text 1</fo:inline>
            </fo:block>
          </fo:block>
          <!-- body's space (after) filler -->
          <fo:block
            space-after.optimum="96px"
            space-after.maximum="96px"
            space-after.conditionality="retain"/>
        </fo:block>
      </fo:block-container>
      <!-- region (r2) -->
      <fo:block-container id="r2" absolute-position="absolute"
        left="10px" top="300px" width="620px" height="96px"
        background-color="black" display-align="center">
        <!-- body (b1) -->
        <fo:block id="b1-2">
          <!-- body's space (before) filler -->
          <fo:block
            space-after.optimum="96px"
            space-after.maximum="96px"
            space-after.conditionality="retain"/>
          <!-- div (d1) -->
          <fo:block id="d1-2">
            <!-- p (p2) -->
            <fo:block id="p2" text-align="center">
              <fo:inline font-size="40px" font-weight="bold"
              color="yellow">Text 2</fo:inline>
            </fo:block>
          </fo:block>
          <!-- body's space (after) filler -->
          <fo:block
            space-after.optimum="96px"
            space-after.maximum="96px"
            space-after.conditionality="retain"/>
        </fo:block>
      </fo:block-container>
    </fo:flow>
  </fo:page-sequence>
</fo:root>

The following, second intermediate document shows the synchronic state for time interval [1,2), during which time both divisions d1 and d2 are temporally active, and where paragraphs p1 and p4 (and their ancestors) are associated with region r1 and paragraphs p2 and p3 (and their ancestors) are associated with region r2.

Example – Intermediate Document – [1s,2s)
<tt tts:extent="640px 480px" xml:lang="en"
  xmlns="http://www.w3.org/ns/ttml"
  xmlns:tts="http://www.w3.org/ns/ttml#styling">
  <head>
    <layout>
      <region xml:id="r1">
        <style tts:origin="10px 100px"/>
        <style tts:extent="620px 96px"/>
        <style tts:fontSize="40px"/>
        <style tts:fontWeight="bold"/>
        <style tts:backgroundColor="black"/>
        <style tts:color="red"/>
        <style tts:textAlign="center"/>
        <style tts:displayAlign="center"/>
        <body xml:id="b1-1">
          <div xml:id="d1-1">
            <p xml:id="p1">Text 1</p>
          </div>
          <div xml:id="d2-1">
            <p xml:id="p4">Text 4</p>
          </div>
        </body>
      </region>
      <region xml:id="r2">
        <style tts:origin="10px 300px"/>
        <style tts:extent="620px 96px"/>
        <style tts:fontSize="40px"/>
        <style tts:fontWeight="bold"/>
        <style tts:backgroundColor="black"/>
        <style tts:color="yellow"/>
        <style tts:textAlign="center"/>
        <style tts:displayAlign="center"/>
        <body xml:id="b1-2">
          <div xml:id="d1-2">
            <p xml:id="p2">Text 2</p>
          </div>
          <div xml:id="d2-2">
            <p xml:id="p3">Text 3</p>
          </div>
        </body>
      </region>
    </layout>
  </head>
</tt>

The following, third intermediate document shows the synchronic state for time interval [2,3), during which time only division d2 is temporally active, and where paragraphs p4 and p3 (and their ancestors) are associated with regions r1 and r2, respectively.

Example – Intermediate Document – [2s,3s)
<tt tts:extent="640px 480px" xml:lang="en"
  xmlns="http://www.w3.org/ns/ttml"
  xmlns:tts="http://www.w3.org/ns/ttml#styling">
  <head>
    <layout>
      <region xml:id="r1">
        <style tts:origin="10px 100px"/>
        <style tts:extent="620px 96px"/>
        <style tts:fontSize="40px"/>
        <style tts:fontWeight="bold"/>
        <style tts:backgroundColor="black"/>
        <style tts:color="red"/>
        <style tts:textAlign="center"/>
        <style tts:displayAlign="center"/>
        <body xml:id="b1-1">
          <div xml:id="d2-1">
            <p xml:id="p4">Text 4</p>
          </div>
        </body>
      </region>
      <region xml:id="r2">
        <style tts:origin="10px 300px"/>
        <style tts:extent="620px 96px"/>
        <style tts:fontSize="40px"/>
        <style tts:fontWeight="bold"/>
        <style tts:backgroundColor="black"/>
        <style tts:color="yellow"/>
        <style tts:textAlign="center"/>
        <style tts:displayAlign="center"/>
        <body xml:id="b1-2">
          <div xml:id="d2-2">
            <p xml:id="p3">Text 3</p>
          </div>
        </body>
      </region>
    </layout>
  </head>
</tt>

9.4 Line Layout

If a profile that applies to a Document Instance requires use of the #lineBreak-uax14 feature (i.e., the value attribute for the feature is specified as use), then the recommendations defined by Line Breaking Algorithm [UAX14] apply when performing line layout on the content of the Document Instance.

10 Timing

This section specifies the timing matter of the core vocabulary catalog, where timing is to be understood as a separable layer of information that applies to content and that denotes authorial intentions about the temporal presentation of that content.

10.1 Timing Element Vocabulary

No timing related element vocabulary is defined for use in the core vocabulary catalog.

10.2 Timing Attribute Vocabulary

This section defines the following basic timing attributes for use with timed elements:

In addition, this section defines the 10.2.4 timeContainer attribute for use with timed elements that serve simultaneously as timing containers.

10.2.1 begin

The begin attribute is used to specify the begin point of a temporal interval associated with a timed element. If specified, the value of a begin attribute must adhere to a <timeExpression> specification as defined by 10.3.1 <timeExpression>.

The begin point of a temporal interval is included in the interval; i.e., the interval is left-wise closed.

The semantics of the begin attribute are those defined by [SMIL 2.1], § 10.4.1, while taking into account any overriding semantics defined by this specification.

Note:

See [SMIL 2.1], § 10.4.1, Begin value semantics when no begin attribute is specified.

10.2.2 end

The end attribute is used to specify the ending point of a temporal interval associated with a timed element. If specified, the value of an end attribute must adhere to a <timeExpression> specification as defined by 10.3.1 <timeExpression>.

The ending point of a temporal interval is not included in the interval; i.e., the interval is right-wise open.

The presentation effects of a non-empty active temporal interval include the frame immediately prior to the frame (or tick) equal to or immediately following the time specified by the ending point, but do not extend into this latter frame (or tick).

Note:

For example, if an active interval is [10s,10.33333s), and the frame rate is 30 frames per second, then the presentation effects of the interval are limited to frames 300 through 309 only (assuming that 0s corresponds with frame 0). The same holds if the active interval is specified as [300f,310f).

The semantics of the end attribute are those defined by [SMIL 2.1], § 10.4.1, while taking into account any overriding semantics defined by this specification.

10.2.3 dur

The dur attribute is used to specify the duration of a temporal interval associated with a timed element. If specified, the value of a dur attribute must adhere to a <timeExpression> specification as defined by 10.3.1 <timeExpression>.

Note:

When the clock-time form of a <timeExpression> specification is used with a dur attribute, it is intended to be interpreted as a difference between two implied clock time expressions.

When a Document Instance specifies the use of the smpte time base and discontinuous marker mode, a (well-formed) dur attribute must not be specified on any element.

The semantics of the dur attribute are those defined by [SMIL 2.1], § 10.4.1, while taking into account any overriding semantics defined by this specification.

Note:

In the context of the subset of [SMIL 2.1] semantics supported by this specification, the active duration of an element that specifies both end and dur attributes is equal to the lesser of the value of the dur attribute and the difference between the value of the end attribute and the element's begin time.

10.2.4 timeContainer

The timeContainer attribute is used to specify a local temporal context by means of which timed child elements are temporally situated.

If specified, the value of a timeContainer attribute must be one of the following:

  • par

  • seq

If the time container semantics of an element instance is par, then the temporal intervals of child elements are considered to apply in parallel, i.e., simultaneously in time. Furthermore, the specification of the time interval of each child element is considered to be relative to the temporal interval of the container element instance. For the purpose of determining the [SMIL 2.1] endsync semantics of a par time container, a default value of all applies.

Note:

The use of a default value of all for the endsync behavior is distinct from [SMIL 2.1] which uses a default value of last.

If the time container semantics of an element instance is seq, then the temporal intervals of child elements are considered to apply in sequence, i.e., sequentially in time. Furthermore, the specification of the time interval of each child element is considered to be relative to the temporal interval of its sibling elements, unless it is the first child element, in which case it is considered to be relative to the temporal interval of the container element instance.

Each time container is considered to constitute an independent time base, i.e., time coordinate system.

If a timeContainer attribute is not specified on an element that has time container semantics, then par time container semantics must apply.

Time container semantics applies only to the following element types:

The semantics of parallel and sequential time containment are those defined by [SMIL 2.1], § 10.4.2, while taking into account any overriding semantics defined by this specification.

10.3 Time Value Expressions

Timing attribute values include the use of the following expressions:

10.3.1 <timeExpression>

A <timeExpression> is used to specify a coordinate within some time base, where the applicable time base is determined by the ttp:timeBase parameter, and where the semantics defined by N Time Expression Semantics apply.

Note:

See 6.2.4 ttp:frameRate, 6.2.9 ttp:subFrameRate, 6.2.10 ttp:tickRate, and 6.2.11 ttp:timeBase for further information on explicit specification of frame rate, sub-frame rate, tick rate, and time base.

Syntax Representation – <timeExpression>
<timeExpression>
  : clock-time
  | offset-time

clock-time
  : hours ":" minutes ":" seconds ( fraction | ":" frames ( "." sub-frames )? )?

offset-time
  : time-count fraction? metric

hours
  : <digit> <digit>
  | <digit> <digit> <digit>+

minutes | seconds
  : <digit> <digit>

frames
  : <digit> <digit>
  | <digit> <digit> <digit>+

sub-frames
  : <digit>+

fraction
  : "." <digit>+

time-count
  : <digit>+

metric
  : "h"                 // hours
  | "m"                 // minutes
  | "s"                 // seconds
  | "ms"                // milliseconds
  | "f"                 // frames
  | "t"                 // ticks

If a <timeExpression> is expressed in terms of a clock-time, then leading zeroes are used when expressing hours, minutes, seconds, and frames less than 10. Minutes are constrained to [0…59], while seconds (including any fractional part) are constrained to the closed interval [0,60], where the value 60 applies only to leap seconds. Except when ttp:timeBase is clock and ttp:clockMode is local or utc, use of the special value of 60 seconds to denote a leap second is undefined and should not be used.

If a <timeExpression> is expressed in terms of a clock-time and a frames term is specified, then the value of this term must be constrained to the interval [0…F-1], where F is the frame rate determined by the ttp:frameRate parameter as defined by 6.2.4 ttp:frameRate. It is considered an error if a frames term or f (frames) metric is specified when the clock time base applies.

If a <timeExpression> is expressed in terms of a clock-time and a sub-frames term is specified, then the value of this term must be constrained to the interval [0…S-1], where S is the sub-frame rate determined by the ttp:subFrameRate parameter as defined by 6.2.9 ttp:subFrameRate. It is considered an error if a sub-frames term is specified when the clock time base applies.

If the governing time base is smpte, then (1) the offset-time form is not defined and should not be used, and (2) the fraction seconds component in a clock-time form is not defined and should not be used.

10.4 Time Intervals

The semantics of time containment, durations, and intervals defined by [SMIL 2.1] apply to the interpretation of like-named timed elements and timing vocabulary defined by this specification, given the following constraints:

  • The implicit duration of an anonymous span, a set element, or a span element whose children are exclusively text nodes, is defined as follows: if the parent time container is a parallel time container, then the implicit duration is equivalent to the indefinite duration value as defined by [SMIL 2.1]; if the parent time container is a sequential time container, then the implicit duration is equivalent to zero.

  • The implicit duration of a body element, div element, p element, or span element whose children are not exclusively text nodes, is determined in accordance to (1) whether the element is a parallel or sequential time container, (2) the default endsync semantics defined above by 10.2.4 timeContainer, and (3) the semantics of [SMIL 2.1] as applied to these time containers.

  • The implicit duration of the region element is defined to be equivalent to the indefinite duration value as defined by [SMIL 2.1].

  • If the governing time base is clock, then time expressions are considered to be equivalent to wall-clock based timing in [SMIL 2.1], where the specific semantics of N.1 Clock Time Base apply.

  • If the governing time base is media, then time expressions are considered to be equivalent to offset based timing in [SMIL 2.1], where the specific semantics of N.2 Media Time Base apply.

  • If the governing time base is smpte, then time expressions are considered to be equivalent to either offset based timing or event based timing in [SMIL 2.1], where the specific semantics of N.3 SMPTE Time Base apply.

For the purposes of performing presentation processing, the [construct anonymous spans] procedure is applied before resolving begin and end times of content elements.

The following example illustrates the timing semantics of anonymous spans that are children of sequential and parallel time containers. The words Hello and Allo are both contained in anonymous spans that are children of a sequential time container (the p element). As such, neither Hello nor Allo will be displayed since the implicit duration of the anonymous spans is 0. In contrast, the anonymous span that contains the word Guten and the innermost span that contains the word Tag are children of an element with parallel time container semantics (the outermost span element). As a result, both Guten and Tag will be displayed since the implicit duration of their respective parent anonymous span and span element are indefinite, resulting in the implicit duration of its span, p, div and body ancestors to also be indefinite.

Example Fragment – Timing of Anonymous Spans in a Sequential and Parallel Time Containers
...
<body>
  <div>
    <p timeContainer="seq">
      Hello
      <span>Guten <span>Tag</span></span>
      Allo
    </p>
  </div>
</body>

11 Animation

This section specifies the animation matter of the core vocabulary catalog, where animation is to be understood as a separable layer of information that combines timing and styling in order to denote authorial intention about (temporally) dynamic styling of content.

11.1 Animation Element Vocabulary

The following elements specify the structure and principal animation aspects of a Document Instance:

11.1.1 set

The set element is used as a child element of a Content element or a region element in order to express a discrete change of some style parameter value that applies over some time interval.

The set element accepts as its children zero or more elements in the Metadata.class element group.

XML Representation – Element Information Item: set
<set
  begin = <timeExpression>
  dur = <timeExpression>
  end = <timeExpression>
  xml:id = ID
  xml:lang = string
  xml:space = (default|preserve)
  {a single attribute in TT Style namespace}
  {any attribute not in default or any TT namespace}>
  Content: Metadata.class*
</set>

Note:

The use of multiple set element children may be used to effect fade and position transitions.

An example of using the set element to animate content styling is illustrated below:

Example Fragment – Content Style Animation
...
<p dur="5s" tts:color="yellow">
<set begin="1s" dur="1s" tts:color="red"/>
<set begin="2s" dur="1s" tts:color="green"/>
<set begin="3s" dur="1s" tts:color="red"/>
Text with Flashing Colors!
</p>
...

Note:

In the above example, the foreground color of the content "Text with Flashing Colors" is animated from yellow, to red, to green, to red, then back to yellow over a 5 second period.

An example of using the set element to animate region styling is illustrated below:

Example Fragment – Region Style Animation
<tt xml:lang="" xmlns="http://www.w3.org/ns/ttml"
    xmlns:ttp="http://www.w3.org/ns/ttml#parameter"
    xmlns:tts="http://www.w3.org/ns/ttml#styling"
    ttp:cellResolution="40 16">
    <head>
      <layout>
	<region xml:id="r1" timeContainer="seq">
	  <set dur="10s" tts:origin=" 8c 14c"/>
	  <set dur="2s"  tts:origin=" 2c  2c"/>
	  <set dur="3s"  tts:origin=" 8c 14c"/>
	  <set dur="2s"  tts:origin="14c  4c"/>
	  <set dur="10s" tts:origin=" 8c 14c"/>
	  <style tts:extent="24c 2c"/>
	</region>
      </layout>
    </head>
    <body region="r1">...</body>
</tt>

Note:

In the above example, the Root Container Region is divided into a cell grid of 40 columns and 16 rows. A region, r1, with dimensions of 24 columns and 2 rows is then positioned within the Root Container Region, with its position varying over time in order to create an effect of moving the region, which may be desirable so as to avoid obscuring characters in an underlying video with captions.

Note:

The semantics of the set element are based upon that defined by [SVG 1.1], § 6.2.13.

11.2 Animation Attribute Vocabulary

No animation related attribute vocabulary is defined for use in the core vocabulary catalog.

12 Metadata

This section specifies the metadata matter of the core vocabulary catalog, where metadata is to be understood as a separable layer of information that applies to parameters, content, style, layout, timing, and even metadata itself, where the information represented by metadata takes one of two forms: (1) metadata defined by this specification for standardized use in a Document Instance, and (2) arbitrary metadata defined outside of the scope of this specification, whose use and semantics depend entirely upon an application's use of TTML Content.

12.1 Metadata Element Vocabulary

The 12.1.1 metadata element serves as a generic container element for grouping metadata information.

In addition, the following elements, all defined in the TT Metadata Namespace, provide standard representations for metadata that is expected to be commonly used in a Document Instances:

12.1.1 metadata

The metadata element functions as a generic container for metadata information.

Metadata information may be expressed with a metadata element by specifying (1) one or more metadata attributes on the metadata element, (2) one or more metadata child elements in the metadata element, or (3) a combination of metadata attributes and metadata child elements. Both types of metadata information are referred to in this document as metadata items.

XML Representation – Element Information Item: metadata
<metadata
  xml:id = ID
  xml:lang = string
  xml:space = (default|preserve)
  {any attribute in TT Metadata namespace}
  {any attribute not in default or any TT namespace}>
  Content: ({any element in TT Metadata namespace}|{any element not in any TT namespace})*
</metadata>

Note:

The meaning of a specific metadata item must be evaluated in the context where it appears. The core vocabulary catalog permits an arbitrary number of metadata element children on any Content element type. See specific element vocabulary definitions for any constraints that apply to such usage.

The use of document metadata is illustrated by the following example.

Example Fragment – Document Metadata
...
<head>
  <metadata xmlns:ttm="http://www.w3.org/ns/ttml#metadata">
    <ttm:title>Document Metadata Example</ttm:title>
    <ttm:desc>This document employs document metadata.</ttm:desc>
  </metadata>
</head>
...

The use of element metadata is illustrated by the following example.

Example Fragment – Element Metadata
...
<div>
  <metadata xmlns:ttm="http://www.w3.org/ns/ttml#metadata">
    <ttm:title>Chapter 6 – Sherlock Holmes Gives a Demonstration</ttm:title>
    <ttm:desc>Holmes shows Watson how the murderer entered the window.</ttm:desc>
  </metadata>
</div>
...

The use of metadata attribute items is illustrated by the following example.

Example Fragment – Foreign Metadata Attribute Items
...
<div xmlns:ext="http://example.org/ttml#metadata">
  <metadata ext:ednote="remove this division prior to publishing"/>
</div>
...

Note:

In the above example, a global attribute from a foreign (external) namespace is used to express a metadata attribute that applies semantically to the containing div element. Note that the attribute may also be expressed directly on the div element; however, in this case the author wishes to segregate certain metadata attributes by expressing them indirectly on metadata elements.

The use of foreign element metadata is illustrated by the following example.

Example Fragment – Foreign Element Metadata
...
<metadata
  xmlns:dc="http://purl.org/dc/elements/1.1/"
  xmlns:dcterms="http://purl.org/dc/terms/"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <dc:title>Foreign Element Metadata Example</dc:title>
  <dc:description>Express metadata using elements in foreign namespace.</dc:description>
  <dc:format xsi:type="dcterms:IMT">application/ttml+xml</dc:format>
</metadata>
...

Note:

In the above example, a number of elements defined by the Dublin Core metadata vocabulary are used to express document level metadata.

12.1.2 ttm:title

The ttm:title element is used to express a human-readable title of a specific element instance.

XML Representation – Element Information Item: ttm:title
<ttm:title
  xml:id = ID
  xml:lang = string
  xml:space = (default|preserve)
  {any attribute not in default or any TT namespace}>
  Content: #PCDATA
</ttm:title>

Note:

No specific use of the ttm:title element is defined by this specification.

Examples of the ttm:title element are shown above in Example Fragment – Document Metadata and Example Fragment – Element Metadata.

12.1.3 ttm:desc

The ttm:desc element is used to express a human-readable description of a specific element instance.

XML Representation – Element Information Item: ttm:desc
<ttm:desc
  xml:id = ID
  xml:lang = string
  xml:space = (default|preserve)
  {any attribute not in default or any TT namespace}>
  Content: #PCDATA
</ttm:desc>

Note:

No specific use of the ttm:desc element is defined by this specification.

Examples of the ttm:desc element are shown above in Example Fragment – Document Metadata and Example Fragment – Element Metadata.

12.1.4 ttm:copyright

The ttm:copyright element is used to express a human-readable copyright that applies to some scoping level.

A copyright statement that applies to a document as a whole should appear as a child of the head element.

XML Representation – Element Information Item: ttm:copyright
<ttm:copyright
  xml:id = ID
  xml:lang = string
  xml:space = (default|preserve)
  {any attribute not in default or any TT namespace}>
  Content: #PCDATA
</ttm:copyright>

Note:

No specific use of the ttm:copyright element is defined by this specification.

12.1.5 ttm:agent

The ttm:agent element is used to define an agent for the purpose of associating content information with an agent who is involved in the production or expression of that content.

The ttm:agent element accepts as its children zero or more ttm:name elements followed by zero or one ttm:actor element.

At least one ttm:name element child should be specified that expresses a name for the agent, whether it be the name of a person, character, group, or organization.

XML Representation – Element Information Item: ttm:agent
<ttm:agent
  type = (person|character|group|organization|other)
  xml:id = ID
  xml:lang = string
  xml:space = (default|preserve)
  {any attribute not in default or any TT namespace}>
  Content: ttm:name*, ttm:actor?
</ttm:agent>

A type attribute must be specified on each ttm:agent element, and, if specified, must have one of the following values:

  • person

  • character

  • group

  • organization

  • other

If the value of the type attribute is character, then the ttm:agent element instance should specify a ttm:actor child that specifies the agent that plays the role of the actor.

A ttm:agent metadata item is considered to be significant only when specified as a child of the head element or as a child of a metadata element child of the head element.

Note:

A ttm:agent element instance is typically referenced using a ttm:agent attribute on a Content element type.

Note:

If a character agent is played by multiple actors, then multiple character agents may be specified (and referenced) wherein different definitions of the character specify different actors.

The use of agent metadata is illustrated by the following example.

Example Fragment – Agent Metadata

<tt xml:lang="en" xmlns="http://www.w3.org/ns/ttml" xmlns:ttm="http://www.w3.org/ns/ttml#metadata">
  <head>
    <ttm:agent xml:id="connery" type="person">
      <ttm:name type="family">Connery</ttm:name>
      <ttm:name type="given">Thomas Sean</ttm:name>
      <ttm:name type="alias">Sean</ttm:name>
      <ttm:name type="full">Sir Thomas Sean Connery</ttm:name>
    </ttm:agent>
    <ttm:agent xml:id="bond" type="character">
      <ttm:name type="family">Bond</ttm:name>
      <ttm:name type="given">James</ttm:name>
      <ttm:name type="alias">007</ttm:name>
      <ttm:actor agent="connery"/>
    </ttm:agent>
  </head>
  <body>
    <div>
      ...  
      <p ttm:agent="bond">I travel, a sort of licensed troubleshooter.</p>
      ...  
    </div>
  </body>
</tt>

Note:

In the above example, two agents, a real (person) agent, Sean Connery, and a fictitious (character) agent, James Bond, are defined, where the latter is linked to the former by means of the a ttm:actor element. A reference is then made from content (the p element) to the character agent associated with (responsible for producing) that content. Note that in this example the ttm:agent metadata items are specified as immediate children of the document's head element rather than being placed in a container metadata element.

12.1.6 ttm:name

The ttm:name element is used to specify a name of a person, character, group, or organization.

XML Representation – Element Information Item: ttm:name
<ttm:name
  type = (full|family|given|alias|other)
  xml:id = ID
  xml:lang = string
  xml:space = (default|preserve)
  {any attribute not in default or any TT namespace}>
  Content: #PCDATA
</ttm:name>

A type attribute must be specified on each ttm:name element, and, if specified, must have one of the following values:

  • full

  • family

  • given

  • alias

  • other

The relationship between the type of a name and the syntactic expression of the name is not defined by this specification.

Two examples of the ttm:name element are shown above in Example Fragment – Agent Metadata.

12.1.7 ttm:actor

The ttm:actor element is used to link the definition of a (role-based) character agent with another agent that portrays the character.

XML Representation – Element Information Item: ttm:actor
<ttm:actor
  agent = IDREF
  xml:id = ID
  xml:lang = string
  xml:space = (default|preserve)
  {any attribute not in default or any TT namespace}>
  Content: EMPTY
</ttm:actor>

The agent attribute of a ttm:actor element must reference a significant ttm:agent element that denotes the agent acting the part of a character.

An ttm:actor element referencing its parent ttm:agent element should be considered an error.

Note:

The semantics of an ttm:actor element referencing its parent ttm:agent element are not defined. While discouraged, the relationship is syntactically permitted. It is therefore recommended that implementations be prepared to process this syntax, e.g. by avoiding infinite loops etc.

Note:

In the case of an actor playing themselves, like Steve Coogan in The Trip playing Steve Coogan, the expected practice is to use two ttm:agent elements. The first element (corresponding to Steve Coogan the person) has type attribute equal to person, while the second element (corresponding to Steve Coogan the character) has (i) a type attribute equal to character and (ii) a child ttm:actor element that references the first ttm:agent element.

An example of the ttm:actor element is shown above in Example Fragment – Agent Metadata.

12.2 Metadata Attribute Vocabulary

This section specifies the following attributes in the TT Metadata Namespace for use with the metadata element and with certain Content element types:

Note:

Only certain metadata item attributes may be used with Content elements. See the definitions of Content elements to determine permissible usage.

12.2.1 ttm:agent

The ttm:agent attribute takes an IDREFS value, and is used with certain Content elements to designate the agents that perform or are involved in the performance of the content.

If specified, a ttm:agent attribute must reference significant ttm:agent element instances.

The same IDREF, ID, should not appear more than once in the value of a ttm:agent attribute.

Note:

This constraint is intended to discourage the use of redundant agent references.

An example of the ttm:agent attribute is shown above in Example Fragment – Agent Metadata.

12.2.2 ttm:role

The ttm:role attribute may be used by a content author to express the roles, functions, or characteristics of some Content element that is so labeled.

If specified, the value of this attribute must adhere to the following syntax, where the syntactic element S must adhere to production [3] S as defined by [XML 1.0] § 2.3:

Syntax Representation – ttm:role
ttm:role
  role ( S role )*

role
  : "action"
  | "caption"
  | "description"
  | "dialog"
  | "expletive"
  | "kinesic"
  | "lyrics"
  | "music"
  | "narration"
  | "quality"
  | "sound"
  | "source"
  | "suppressed"
  | "reproduction"
  | "thought"
  | "title"
  | "transcription"
  | extension-role

extension-role
  : "x-" token-char+

token-char
  : { XML NameChar }    // XML 1.1 Production [4a]

The same role token, R, should not appear more than once in the value of a ttm:role attribute.

Note:

This constraint is intended to discourage the use of redundant role tokens.

Note:

All values of ttm:role that do not start with the prefix x- are reserved for future standardization.

Note:

If using a custom x- prefixed form of ttm:role, it is recommended that an organization unique infix be used as well in order to prevent collisions. For example, x-example-org-custom-role. Furthermore, a registry for role values is available at http://www.w3.org/wiki/TTML/RoleRegistry in order to promote interoperability and collision avoidance.

A Reduced XML Infoset

This appendix is normative.

For the purposes of this specification, a Reduced XML Infoset is an XML Information Set [XML InfoSet] that consists of only the following information items and information item properties:

A.1 Document Information Item

  • [document element]

A.2 Element Information Item

  • [namespace URI]

  • [local name]

  • [children]

  • [attributes]

Child information items [children] are reduced to only element and character information items.

A.3 Attribute Information Item

  • [namespace URI]

  • [local name]

  • [normalized value]

A.4 Character Information Item

  • [character code]

Contiguous character information items are not required to be represented distinctly, but may be aggregated (chunked) into a sequence of character codes (i.e., a character string).

B Schemas

This appendix is normative.

This appendix specifies the following schemas for use with Document Instances:

In any case where a schema specified by this appendix differs from the normative definitions of document type, element type, or attribute type as defined by the body of this specification, then the body of this specification takes precedence.

B.1 Relax NG Compact (RNC) Schema

A Relax NG Compact Syntax (RNC) [RELAX NG] based schema for TTML Content is available at ZIP Archive. This schema does not normatively define the validity of Timed Text Markup Language content as defined by this specification. In particular, the formal validity of TTML Content is defined by 3.1 Content Conformance.

B.2 XML Schema Definition (XSD) Schema

A W3C XML Schema Definition (XSD) [XML Schema Part 1] based schema for TTML Content is available at ZIP Archive. This schema does not normatively define the validity of Timed Text Markup Language content as defined by this specification. In particular, the formal validity of TTML Content is defined by 3.1 Content Conformance.

C Media Type Registration

This appendix is normative.

This appendix registers a new media type, "application/ttml+xml" in conformance with BCP 13 and W3CRegMedia. The information in this appendix is being submitted to the Internet Engineering Steering Group (IESG) for review, approval, and registration with the Internet Assigned Numbers Authority (IANA).

Type name:

application

Subtype name:

ttml+xml

Required parameters:

None.

Optional parameters:
charset

If specified, the charset parameter must match the XML encoding declaration, or if absent, the actual encoding. See also Encoding Considerations below.

profile

The document profile of a TTMLDocument Instance may be specified using an optional profile parameter, which, if specified, the value of which must adhere to the syntax and semantics of ttp:profile parameter defined by Section 6.2.8 ttp:profile of the published specification.

Encoding considerations:

Same for application/xml, except constrained to either UTF-8 or UTF-16. See [XML Media Types] (http://www.rfc-editor.org/rfc/rfc3023.txt), Section 3.2. For the purpose of filling out the IANA Application for Media Type (http://www.iana.org/cgi-bin/mediatypes.pl), the value binary applies.

Security considerations:

As with other XML types and as noted in [XML Media Types] (http://www.rfc-editor.org/rfc/rfc3023.txt), Section 10, repeated expansion of maliciously constructed XML entities can be used to consume large amounts of memory, which may cause XML processors in constrained environments to fail.

In addition, because of the extensibility features for TTML and of XML in general, it is possible that "application/ttml+xml" may describe content that has security implications beyond those described here. However, TTML does not provide for any sort of active or executable content, and if the processor follows only the normative semantics of the published specification, this content will be outside TTML namespaces and may be ignored. Only in the case where the processor recognizes and processes the additional content, or where further processing of that content is dispatched to other processors, would security issues potentially arise. And in that case, they would fall outside the domain of this registration document.

Although not prohibited, there are no expectations that XML signatures or encryption would normally be employed.

Interoperability considerations:

The published specification describes processing semantics that dictate behavior that must be followed when dealing with, among other things, unrecognized elements and attributes, both in TTML namespaces and in other namespaces.

Because TTML is extensible, conformant "application/ttml+xml" processors may expect (and enforce) that content received is well-formed XML, but it cannot be guaranteed that the content is valid to a particular DTD or Schema or that the processor will recognize all of the elements and attributes in the document.

Published specification:

This media type registration is extracted from Appendix C Media Type Registration of the Timed Text Markup Language (TTML) 1.0 specification: Timed Text Markup Language 1 (TTML1).

Applications that use this media type:

TTML is used in the television industry for the purpose of authoring, transcoding and exchanging timed text information and for delivering captions, subtitles, and other metadata for television material repurposed for the Web or, more generally, the Internet.

There is partial and full support of TTML in components used by several Web browsers plugins, and in a number of caption authoring tools.

Additional information:
Magic number(s):
File extension(s):

.ttml

Macintosh file type code(s):

"TTML"

Fragment identifiers:

For documents labeled as application/ttml+xml, the fragment identifier notation is intended to be used with xml:id attributes, as described in section 7.2.1 of the Timed Text Markup Language 1 (TTML1) specification.

Person & email address to contact for further information:

Timed Text Working Group (public-tt@w3.org)

Intended usage:

COMMON

Restrictions on usage:

None

Author:

The published specification is a work product of the World Wide Web Consortium's Timed Text (TT) Working Group.

Change controller:

The W3C has change control over this specification.

D Features

This appendix is normative.

This appendix specifies (1) a set of feature designations, each of which labels one or more syntactic and/or semantic features defined by this specification, and (2) for each designated feature, whether the feature is mandatory or optional for a transformation or presentation processor.

Note:

A TTML processor is said to implement the transformation semantics or implement the presentation semantics of feature designation F if it satisfies the requirements of this appendix with respect to the definition of feature designation F as pertains to transformation or presentation processing, respectively.

D.1 Feature Designations

A feature designation is expressed as a string that adheres to the following form:

feature-designation
  : feature-namespace designation

feature-namespace
  : TT Feature Namespace                    // http://www.w3.org/ns/ttml/feature/

designation
  : "#" token-char+

token-char
  : { XML NameChar }                        // XML 1.1 Production [4a]

All values of feature-designation not defined by this specification are reserved for future standardization.

The following sub-sections define all feature designations, expressed as relative URIs (fragment identifiers) with respect to the TT Feature Namespace base URI.

D.1.1 #animation

A TTML transformation processor supports the #animation feature if it recognizes and is capable of transforming the following vocabulary defined by 11 Animation:

A TTML presentation processor supports the #animation feature if it implements presentation semantic support for the same vocabulary enumerated above.

D.1.2 #backgroundColor

A TTML transformation processor supports the #backgroundColor feature if it recognizes and is capable of transforming the tts:backgroundColor attribute.

A TTML presentation processor supports the #backgroundColor feature if it (1) implements presentation semantic support for the tts:backgroundColor attribute and (2) is capable of displaying or generating an output display signal that distinguishes between at least sixteen (16) values of color, including all primary and secondary colors of the SRGB color space.

Note:

Support for this feature is intended to imply support for the following features: #backgroundColor-block, #backgroundColor-region, and #backgroundColor-inline.

D.1.3 #backgroundColor-block

A TTML transformation processor supports the #backgroundColor-block feature if it recognizes and is capable of transforming all defined values of the tts:backgroundColor attribute when applied to a content element that would generate a block area during presentation processing.

A TTML presentation processor supports the #backgroundColor-block feature if it (1) implements presentation semantic support for the tts:backgroundColor attribute when applied to a content element that generates a block area and (2) is capable of displaying or generating an output display signal that distinguishes between at least sixteen (16) values of color, including all primary and secondary colors of the SRGB color space.

D.1.4 #backgroundColor-inline

A TTML transformation processor supports the #backgroundColor-inline feature if it recognizes and is capable of transforming all defined values of the tts:backgroundColor attribute when applied to a content element that would generate an inline area during presentation processing.

A TTML presentation processor supports the #backgroundColor-inline feature if it (1) implements presentation semantic support for the tts:backgroundColor attribute when applied to a content element that generates an inline area and (2) is capable of displaying or generating an output display signal that distinguishes between at least sixteen (16) values of color, including all primary and secondary colors of the SRGB color space.

D.1.5 #backgroundColor-region

A TTML transformation processor supports the #backgroundColor-region feature if it recognizes and is capable of transforming all defined values of the tts:backgroundColor attribute when applied to a region element.

A TTML presentation processor supports the #backgroundColor-region feature if it (1) implements presentation semantic support for the tts:backgroundColor attribute when applied to a region element and (2) is capable of displaying or generating an output display signal that distinguishes between at least sixteen (16) values of color, including all primary and secondary colors of the SRGB color space .

D.1.6 #bidi

A TTML processor supports the #bidi feature if it supports the following features:

D.1.7 #cellResolution

A TTML transformation processor supports the #cellResolution feature if it recognizes and is capable of transforming the ttp:cellResolution attribute.

A TTML presentation processor supports the #cellResolution feature if it implements presentation semantic support for the ttp:cellResolution attribute.

D.1.8 #clockMode

A TTML transformation processor supports the #clockMode feature if it recognizes and is capable of transforming the ttp:clockMode attribute.

A TTML presentation processor supports the #clockMode feature if it implements presentation semantic support for the ttp:clockMode attribute.

D.1.9 #clockMode-gps

A TTML transformation processor supports the #clockMode-gps feature if it recognizes and is capable of transforming the gps value of the ttp:clockMode attribute.

A TTML presentation processor supports the #clockMode-gps feature if it implements presentation semantic support for the gps value of the ttp:clockMode attribute.

D.1.10 #clockMode-local

A TTML transformation processor supports the #clockMode-local feature if it recognizes and is capable of transforming the local value of the ttp:clockMode attribute.

A TTML presentation processor supports the #clockMode-local feature if it implements presentation semantic support for the local value of the ttp:clockMode attribute.

D.1.11 #clockMode-utc

A TTML transformation processor supports the #clockMode-utc feature if it recognizes and is capable of transforming the utc value of the ttp:clockMode attribute.

A TTML presentation processor supports the #clockMode-utc feature if it implements presentation semantic support for the utc value of the ttp:clockMode attribute.

D.1.12 #color

A TTML transformation processor supports the #color feature if it recognizes and is capable of transforming the tts:color attribute.

A TTML presentation processor supports the #color feature if it (1) implements presentation semantic support for the tts:color attribute and (2) is capable of displaying or generating an output display signal that distinguishes between at least sixteen (16) values of color, including all primary and secondary colors of the SRGB color space.

D.1.13 #content

A TTML transformation processor supports the #content feature if it recognizes and is capable of transforming the following vocabulary defined by 7 Content:

A TTML presentation processor supports the #content feature if it implements presentation semantic support for the same vocabulary enumerated above.

D.1.14 #core

A TTML transformation processor supports the #core feature if it recognizes and is capable of transforming the following core attributes vocabulary defined by 7 Content:

A TTML presentation processor supports the #core feature if it implements presentation semantic support for the same vocabulary enumerated above.

D.1.15 #direction

A TTML transformation processor supports the #direction feature if it recognizes and is capable of transforming all defined values of the tts:direction attribute.

A TTML presentation processor supports the #direction feature if it implements presentation semantic support for all defined values of the tts:direction attribute.

D.1.16 #display

A TTML transformation processor supports the #display feature if it recognizes and is capable of transforming all defined values of the tts:display attribute.

A TTML presentation processor supports the #display feature if it implements presentation semantic support for all defined values of the tts:display attribute.

D.1.17 #display-block

A TTML transformation processor supports the #display-block feature if it recognizes and is capable of transforming all defined values of the tts:display attribute when applied to a content element that would generate a block area during presentation processing.

A TTML presentation processor supports the #display-block feature if it implements presentation semantic support for all defined values of the tts:display attribute when applied to a content element that generates a block area.

D.1.18 #display-inline

A TTML transformation processor supports the #display-inline feature if it recognizes and is capable of transforming all defined values of the tts:display attribute when applied to a content element that would generate an inline area during presentation processing.

A TTML presentation processor supports the #display-inline feature if it implements presentation semantic support for all defined values of the tts:display attribute when applied to a content element that generates an inline area.

D.1.19 #display-region

A TTML transformation processor supports the #display-region feature if it recognizes and is capable of transforming all defined values of the tts:display attribute when applied to a region element.

A TTML presentation processor supports the #display-region feature if it implements presentation semantic support for all defined values of the tts:display attribute when applied to a region element.

D.1.20 #displayAlign

A TTML transformation processor supports the #displayAlign feature if it recognizes and is capable of transforming all defined values of the tts:displayAlign attribute.

A TTML presentation processor supports the #displayAlign feature if it implements presentation semantic support for all defined values of the tts:displayAlign attribute.

D.1.21 #dropMode

A TTML transformation processor supports the #dropMode feature if it recognizes and is capable of transforming the ttp:dropMode attribute.

A TTML presentation processor supports the #dropMode feature if it implements presentation semantic support for the ttp:dropMode attribute.

D.1.22 #dropMode-dropNTSC

A TTML transformation processor supports the #dropMode-dropNTSC feature if it recognizes and is capable of transforming the dropNTSC value of the ttp:dropMode attribute.

A TTML presentation processor supports the #dropMode-dropNTSC feature if it implements presentation semantic support for the dropNTSC value of the ttp:dropMode attribute.

D.1.23 #dropMode-dropPAL

A TTML transformation processor supports the #dropMode-dropPAL feature if it recognizes and is capable of transforming the dropPAL value of the ttp:dropMode attribute.

A TTML presentation processor supports the #dropMode-dropPAL feature if it implements presentation semantic support for the dropPAL value of the ttp:dropMode attribute.

D.1.24 #dropMode-nonDrop

A TTML transformation processor supports the #dropMode-nonDrop feature if it recognizes and is capable of transforming the nonDrop value of the ttp:dropMode attribute.

A TTML presentation processor supports the #dropMode-nonDrop feature if it implements presentation semantic support for the nonDrop value of the ttp:dropMode attribute.

D.1.25 #extent

A TTML transformation processor supports the #extent feature if it recognizes and is capable of transforming the tts:extent attribute.

A TTML presentation processor supports the #extent feature if it implements presentation semantic support for the tts:extent attribute.

D.1.26 #extent-region

A TTML transformation processor supports the #extent-region feature if it recognizes and is capable of transforming the tts:extent attribute when applied to a region element.

A TTML presentation processor supports the #extent-region feature if it implements presentation semantic support for the tts:extent attribute when applied to a region element.

D.1.27 #extent-root

A TTML transformation processor supports the #extent-root feature if it recognizes and is capable of transforming the tts:extent attribute when applied to the tt element.

A TTML presentation processor supports the #extent-root feature if it implements presentation semantic support for the tts:extent attribute when applied to a tt element.

D.1.28 #fontFamily

A TTML transformation processor supports the #fontFamily feature if it recognizes and is capable of transforming the tts:fontFamily attribute.

A TTML presentation processor supports the #fontFamily feature if it implements presentation semantic support for the tts:fontFamily attribute.

D.1.29 #fontFamily-generic

A TTML transformation processor supports the #fontFamily-generic feature if it recognizes and is capable of transforming <genericFamilyName> values when used with the tts:fontFamily attribute.

A TTML presentation processor supports the #fontFamily-generic feature if it implements presentation semantic support for <genericFamilyName> values when used with the tts:fontFamily attribute.

D.1.30 #fontFamily-non-generic

A TTML transformation processor supports the #fontFamily-non-generic feature if it recognizes and is capable of transforming <familyName> values when used with the tts:fontFamily attribute.

A TTML presentation processor supports the #fontFamily-non-generic feature if it implements presentation semantic support for <familyName> values when used with the tts:fontFamily attribute.

D.1.31 #fontSize

A TTML transformation processor supports the #fontSize feature if it recognizes and is capable of transforming the tts:fontSize attribute.

A TTML presentation processor supports the #fontSize feature if it implements presentation semantic support for the tts:fontSize attribute.

D.1.32 #fontSize-anamorphic

A TTML transformation processor supports the #fontSize-anamorphic feature if it recognizes and is capable of transforming values of the tts:fontSize attribute that consist of two <length> specifications.

A TTML presentation processor supports the #fontSize-anamorphic feature if it implements presentation semantic support for defined values of the tts:fontSize attribute that consist of two <length> specifications.

D.1.33 #fontSize-isomorphic

A TTML transformation processor supports the #fontSize-isomorphic feature if it recognizes and is capable of transforming values of the tts:fontSize attribute that consist of a single <length> specification.

A TTML presentation processor supports the #fontSize-isomorphic feature if it implements presentation semantic support for defined values of the tts:fontSize attribute that consist of a single <length> specification.

D.1.34 #fontStyle

A TTML transformation processor supports the #fontStyle feature if it recognizes and is capable of transforming all defined values of the tts:fontStyle attribute.

A TTML presentation processor supports the #fontStyle feature if it implements presentation semantic support for all defined values of the tts:fontStyle attribute.

D.1.35 #fontStyle-italic

A TTML transformation processor supports the #fontStyle-italic feature if it recognizes and is capable of transforming the italic value of the tts:fontStyle attribute.

A TTML presentation processor supports the #fontStyle-italic feature if it implements presentation semantic support for the italic of the tts:fontStyle attribute.

D.1.36 #fontStyle-oblique

A TTML transformation processor supports the #fontStyle-oblique feature if it recognizes and is capable of transforming the oblique value of the tts:fontStyle attribute.

A TTML presentation processor supports the #fontStyle-oblique feature if it implements presentation semantic support for the oblique of the tts:fontStyle attribute.

D.1.37 #fontWeight

A TTML transformation processor supports the #fontWeight feature if it recognizes and is capable of transforming all defined values of the tts:fontWeight attribute.

A TTML presentation processor supports the #fontWeight feature if it implements presentation semantic support for all defined values of the tts:fontWeight attribute.

D.1.38 #fontWeight-bold

A TTML transformation processor supports the #fontWeight-bold feature if it recognizes and is capable of transforming bold value of the tts:fontWeight attribute.

A TTML presentation processor supports the #fontWeight-bold feature if it implements presentation semantic support for the bold of the tts:fontWeight attribute.

D.1.39 #frameRate

A TTML transformation processor supports the #frameRate feature if it recognizes and is capable of transforming the ttp:frameRate attribute.

A TTML presentation processor supports the #frameRate feature if it implements presentation semantic support for the ttp:frameRate attribute.

D.1.40 #frameRateMultiplier

A TTML transformation processor supports the #frameRateMultiplier feature if it recognizes and is capable of transforming the ttp:frameRateMultiplier attribute.

A TTML presentation processor supports the #frameRateMultiplier feature if it implements presentation semantic support for the ttp:frameRateMultiplier attribute.

D.1.41 #layout

A TTML transformation processor supports the #layout feature if it (1) recognizes and is capable of transforming the following vocabulary defined by 9 Layout:

and (2) supports the following attributes when applied to the region element:

A TTML presentation processor supports the #layout feature if it implements presentation semantic support for the same vocabulary and features enumerated above.

D.1.42 #length

A TTML transformation processor supports the #length feature if it recognizes and is capable of transforming all defined values of the <length> style value expression.

A TTML presentation processor supports the #length feature if it implements presentation semantic support for all defined values of the <length> style value expression.

Note:

Support for #length is intended to imply support for the following features: #length-integer, #length-real, #length-positive, #length-negative, #length-cell, #length-em, #length-percentage, and #length-pixel.

D.1.43 #length-cell

A TTML transformation processor supports the #length-cell feature if it recognizes and is capable of transforming scalar values of the <length> style value expression that use c (cell) units.

A TTML presentation processor supports the #length-cell feature if it implements presentation semantic support for scalar values of the <length> style value expression that use c (cell) units.

Note:

Support for #length-cell does not, by itself, imply support for #length-integer, #length-real, #length-positive, or #length-negative features.

D.1.44 #length-em

A TTML transformation processor supports the #length-em feature if it recognizes and is capable of transforming scalar values of the <length> style value expression that use em (EM) units.

A TTML presentation processor supports the #length-em feature if it implements presentation semantic support for scalar values of the <length> style value expression that use em (EM) units.

Note:

Support for #length-em does not, by itself, imply support for #length-integer, #length-real, #length-positive, or #length-negative features.

D.1.45 #length-integer

A TTML transformation processor supports the #length-integer feature if it recognizes and is capable of transforming integer values of the <length> style value expression.

A TTML presentation processor supports the #length-integer feature if it implements presentation semantic support for integer values of the <length> style value expression.

Note:

Support for #length-integer does not, by itself, imply support for #length-positive or #length-negative features.

D.1.46 #length-negative

A TTML transformation processor supports the #length-negative feature if it recognizes and is capable of transforming negative values of the <length> style value expression.

A TTML presentation processor supports the #length-negative feature if it implements presentation semantic support for negative values of the <length> style value expression.

Note:

Support for #length-negative does not, by itself, imply support for #length-integer or #length-real features.

D.1.47 #length-percentage

A TTML transformation processor supports the #length-percentage feature if it recognizes and is capable of transforming percentage values of the <length> style value expression.

A TTML presentation processor supports the #length-percentage feature if it implements presentation semantic support for percentage values of the <length> style value expression.

Note:

Support for #length-percentage does not, by itself, imply support for #length-integer, #length-real, #length-positive, or #length-negative features.

D.1.48 #length-pixel

A TTML transformation processor supports the #length-pixel feature if it recognizes and is capable of transforming scalar values of the <length> style value expression that use px (pixel) units.

A TTML presentation processor supports the #length-pixel feature if it implements presentation semantic support for scalar values of the <length> style value expression that use px (pixel) units.

Note:

Support for #length-pixel does not, by itself, imply support for #length-integer, #length-real, #length-positive, or #length-negative features.

D.1.49 #length-positive

A TTML transformation processor supports the #length-positive feature if it recognizes and is capable of transforming positive values of the <length> style value expression.

A TTML presentation processor supports the #length-positive feature if it implements presentation semantic support for positive values of the <length> style value expression.

Note:

Support for #length-positive is intended to imply support for zero valued <length> style value expressions.

Note:

Support for #length-positive does not, by itself, imply support for #length-integer or #length-real features.

D.1.50 #length-real

A TTML transformation processor supports the #length-real feature if it recognizes and is capable of transforming real values of the <length> style value expression.

A TTML presentation processor supports the #length-real feature if it implements presentation semantic support for real values of the <length> style value expression.

Note:

Support for #length-real is intended to imply support for integer valued <length> style value expressions as well as real valued expressions.

Note:

Support for #length-real does not, by itself, imply support for #length-positive or #length-negative features.

D.1.51 #lineBreak-uax14

A TTML transformation processor supports the #lineBreak-uax14 feature if it recognizes and is capable of transforming requirements expressed by [UAX14] into its target document space.

A TTML presentation processor supports the #lineBreak-uax14 feature if it implements presentation semantic support for [UAX14] as applies to line breaking.

D.1.52 #lineHeight

A TTML transformation processor supports the #lineHeight feature if it recognizes and is capable of transforming the tts:lineHeight attribute.

A TTML presentation processor supports the #lineHeight feature if it implements presentation semantic support for the tts:lineHeight attribute.

D.1.53 #markerMode

A TTML transformation processor supports the #markerMode feature if it recognizes and is capable of transforming the ttp:markerMode attribute.

A TTML presentation processor supports the #markerMode feature if it implements presentation semantic support for the ttp:markerMode attribute.

D.1.54 #markerMode-continuous

A TTML transformation processor supports the #markerMode-continuous feature if it recognizes and is capable of transforming the continuous value of the ttp:markerMode attribute.

A TTML presentation processor supports the #markerMode-continuous feature if it implements presentation semantic support for the continuous value of the ttp:markerMode attribute.

D.1.55 #markerMode-discontinuous

A TTML transformation processor supports the #markerMode-discontinuous feature if it recognizes and is capable of transforming the discontinuous value of the ttp:markerMode attribute.

A TTML presentation processor supports the #markerMode-discontinuous feature if it implements presentation semantic support for the discontinuous value of the ttp:markerMode attribute.

D.1.56 #metadata

A TTML transformation processor supports the #metadata feature if it recognizes and is capable of transforming the following vocabulary defined by 12 Metadata:

A TTML presentation processor supports the #metadata feature if it recognizes and is capable of presenting the information expressed by the same vocabulary enumerated above.

Note:

This specification does not define a standardized form for the presentation of metadata information. The presentation or ability to present metadata information is considered to be implementation dependent.

D.1.57 #nested-div

A TTML transformation processor supports the #nested-div feature if it recognizes and is capable of transforming nested div elements.

A TTML presentation processor supports the #nested-div feature if it implements presentation semantic support for nested div elements.

D.1.58 #nested-span

A TTML transformation processor supports the #nested-span feature if it recognizes and is capable of transforming nested span elements.

A TTML presentation processor supports the #nested-span feature if it implements presentation semantic support for nested span elements.

D.1.59 #opacity

A TTML transformation processor supports the #opacity feature if it recognizes and is capable of transforming the tts:opacity attribute.

A TTML presentation processor supports the #opacity feature if it (1) implements presentation semantic support for the tts:opacity attribute and (2) is capable of displaying or generating an output display signal that distinguishes between at least eight (8) values of opacity.

D.1.60 #origin

A TTML transformation processor supports the #origin feature if it recognizes and is capable of transforming the tts:origin attribute.

A TTML presentation processor supports the #origin feature if it implements presentation semantic support for the tts:origin attribute.

D.1.61 #overflow

A TTML transformation processor supports the #overflow feature if it recognizes and is capable of transforming all defined values of the tts:overflow attribute.

A TTML presentation processor supports the #overflow feature if it implements presentation semantic support for all defined values of the tts:overflow attribute.

D.1.62 #overflow-visible

A TTML transformation processor supports the #overflow-visible feature if it recognizes and is capable of transforming the visible value of the tts:overflow attribute.

A TTML presentation processor supports the #overflow-visible feature if it implements presentation semantic support for the visible value of the tts:overflow attribute.

D.1.63 #padding

A TTML transformation processor supports the #padding feature if it recognizes and is capable of transforming the tts:padding attribute.

A TTML presentation processor supports the #padding feature if it implements presentation semantic support for the tts:padding attribute.

D.1.64 #padding-1

A TTML transformation processor supports the #padding-1 feature if it recognizes and is capable of transforming values of the tts:padding attribute that consist of one <length> specification.

A TTML presentation processor supports the #padding-1 feature if it implements presentation semantic support for values of the tts:padding attribute that consist of one <length> specification.

D.1.65 #padding-2

A TTML transformation processor supports the #padding-2 feature if it recognizes and is capable of transforming values of the tts:padding attribute that consist of two <length> specification.

A TTML presentation processor supports the #padding-2 feature if it implements presentation semantic support for values of the tts:padding attribute that consist of two <length> specification.

D.1.66 #padding-3

A TTML transformation processor supports the #padding-3 feature if it recognizes and is capable of transforming values of the tts:padding attribute that consist of three <length> specification.

A TTML presentation processor supports the #padding-3 feature if it implements presentation semantic support for values of the tts:padding attribute that consist of three <length> specification.

D.1.67 #padding-4

A TTML transformation processor supports the #padding-4 feature if it recognizes and is capable of transforming values of the tts:padding attribute that consist of four <length> specification.

A TTML presentation processor supports the #padding-4 feature if it implements presentation semantic support for values of the tts:padding attribute that consist of four <length> specification.

D.1.68 #pixelAspectRatio

A TTML transformation processor supports the #pixelAspectRatio feature if it recognizes and is capable of transforming the ttp:pixelAspectRatio attribute.

A TTML presentation processor supports the #pixelAspectRatio feature if it implements presentation semantic support for the ttp:pixelAspectRatio attribute.

D.1.69 #presentation

A TTML processor supports the #presentation feature if it (1) satisfies the generic processor criteria defined by 3.2.1 Generic Processor Conformance, (2) implements support for the region and line layout semantics defined by 9.3 Region Layout and Presentation and 9.4 Line Layout, respectively, and (3) implements presentation semantics for the following features:

In addition, a TTML processor that supports the #presentation feature should satisfy the user agent accessibility guidelines specified by [UAAG].

D.1.70 #profile

A TTML transformation processor supports the #profile feature if it recognizes and is capable of transforming the ttp:profile attribute on the tt element and transforming the following vocabulary defined by 6.1 Parameter Element Vocabulary:

A TTML presentation processor supports the #profile feature if it implements presentation semantic support for the same vocabulary specified above.

D.1.71 #showBackground

A TTML transformation processor supports the #showBackground feature if it recognizes and is capable of transforming all defined values of the tts:showBackground attribute.

A TTML presentation processor supports the #showBackground feature if it implements presentation semantic support for all defined values of the tts:showBackground attribute.

D.1.72 #structure

A TTML transformation processor supports the #structure feature if it recognizes and is capable of transforming the following vocabulary defined by 7 Content:

A TTML presentation processor supports the #structure feature if it implements presentation semantic support for the same vocabulary enumerated above.

D.1.73 #styling

A TTML transformation processor supports the #styling feature if it recognizes and is capable of transforming the following vocabulary defined by 8 Styling:

A TTML presentation processor supports the #styling feature if it implements presentation semantic support for the same vocabulary enumerated above.

D.1.74 #styling-chained

A TTML transformation processor supports the #styling-chained feature if it recognizes and is capable of transforming chained style association as defined by 8.4.1.3 Chained Referential Styling.

A TTML presentation processor supports the #styling-chained feature if it implements presentation semantic support for chained style association as defined by 8.4.1.3 Chained Referential Styling.

D.1.75 #styling-inheritance-content

A TTML transformation processor supports the #styling-inheritance feature if it recognizes and is capable of transforming content style inheritance as defined by 8.4.2.1 Content Style Inheritance.

A TTML presentation processor supports the #styling-inheritance-content feature if it implements presentation semantic support for content style inheritance as defined by 8.4.2.1 Content Style Inheritance.

D.1.76 #styling-inheritance-region

A TTML transformation processor supports the #styling-inheritance feature if it recognizes and is capable of transforming region style inheritance as defined by 8.4.2.2 Region Style Inheritance.

A TTML presentation processor supports the #styling-inheritance-region feature if it implements presentation semantic support for region style inheritance as defined by 8.4.2.2 Region Style Inheritance.

D.1.77 #styling-inline

A TTML transformation processor supports the #styling-inline feature if it recognizes and is capable of transforming inline style association as defined by 8.4.1.1 Inline Styling.

A TTML presentation processor supports the #styling-inline feature if it implements presentation semantic support for inline style association as defined by 8.4.1.1 Inline Styling.

D.1.78 #styling-nested

A TTML transformation processor supports the #styling-nested feature if it recognizes and is capable of transforming nested style association as defined by 8.4.1.4 Nested Styling.

A TTML presentation processor supports the #styling-nested feature if it implements presentation semantic support for nested style association as defined by 8.4.1.4 Nested Styling.

D.1.79 #styling-referential

A TTML transformation processor supports the #styling-referential feature if it recognizes and is capable of transforming referential style association as defined by 8.4.1.2 Referential Styling.

A TTML presentation processor supports the #styling-referential feature if it implements presentation semantic support for referential style association as defined by 8.4.1.2 Referential Styling.

D.1.80 #subFrameRate

A TTML transformation processor supports the #subFrameRate feature if it recognizes and is capable of transforming the ttp:subFrameRate attribute.

A TTML presentation processor supports the #subFrameRate feature if it implements presentation semantic support for the ttp:subFrameRate attribute.

D.1.81 #textAlign

A TTML transformation processor supports the #textAlign feature if it recognizes and is capable of transforming all defined values of the tts:textAlign attribute.

A TTML presentation processor supports the #textAlign feature if it implements presentation semantic support for all defined values of the tts:textAlign attribute.

D.1.82 #textAlign-absolute

A TTML transformation processor supports the #textAlign-absolute feature if it recognizes and is capable of transforming the left, center, and right values of the tts:textAlign attribute.

A TTML presentation processor supports the #textAlign-absolute feature if it implements presentation semantic support for the left, center, and right values of the tts:textAlign attribute.

D.1.83 #textAlign-relative

A TTML transformation processor supports the #textAlign-relative feature if it recognizes and is capable of transforming the start, center, and end values of the tts:textAlign attribute.

A TTML presentation processor supports the #textAlign-relative feature if it implements presentation semantic support for the start, center, and end values of the tts:textAlign attribute.

D.1.84 #textDecoration

A TTML transformation processor supports the #textDecoration feature if it recognizes and is capable of transforming all defined values of the tts:textDecoration attribute.

A TTML presentation processor supports the #textDecoration feature if it implements presentation semantic support for all defined values of the tts:textDecoration attribute.

D.1.85 #textDecoration-over

A TTML transformation processor supports the #textDecoration-over feature if it recognizes and is capable of transforming the overline and noOverline values of the tts:textDecoration attribute.

A TTML presentation processor supports the #textDecoration-over feature if it implements presentation semantic support for the overline and noOverline values of the tts:textDecoration attribute.

D.1.86 #textDecoration-through

A TTML transformation processor supports the #textDecoration-through feature if it recognizes and is capable of transforming the lineThrough and noLineThrough values of the tts:textDecoration attribute.

A TTML presentation processor supports the #textDecoration-through feature if it implements presentation semantic support for the lineThrough and noLineThrough values of the tts:textDecoration attribute.

D.1.87 #textDecoration-under

A TTML transformation processor supports the #textDecoration-under feature if it recognizes and is capable of transforming the underline and noUnderline values of the tts:textDecoration attribute.

A TTML presentation processor supports the #textDecoration-under feature if it implements presentation semantic support for the underline and noUnderline values of the tts:textDecoration attribute.

D.1.88 #textOutline

A TTML processor supports the #textOutline feature if it supports the following features:

D.1.89 #textOutline-blurred

A TTML transformation processor supports the #textOutline-blurred feature if it recognizes and is capable of transforming values of the tts:textOutline attribute that includes a blur radius specification.

A TTML presentation processor supports the #textOutline-blurred feature if it implements presentation semantic support for values of the tts:textOutline attribute that includes a blur radius specification.

D.1.90 #textOutline-unblurred

A TTML transformation processor supports the #textOutline-unblurred feature if it recognizes and is capable of transforming values of the tts:textOutline attribute that does not include a blur radius specification.

A TTML presentation processor supports the #textOutline-unblurred feature if it implements presentation semantic support for values of the tts:textOutline attribute that does not include a blur radius specification.

D.1.91 #tickRate

A TTML transformation processor supports the #tickRate feature if it recognizes and is capable of transforming the ttp:tickRate attribute.

A TTML presentation processor supports the #tickRate feature if it implements presentation semantic support for the ttp:tickRate attribute.

D.1.92 #timeBase-clock

A TTML transformation processor supports the #timeBase-clock feature if it recognizes and is capable of transforming the clock value of the ttp:timeBase attribute and if it supports the #clockMode feature.

A TTML presentation processor supports the #timeBase-clock feature if it implements presentation semantic support for the clock value of the ttp:timeBase attribute and if it supports the #clockMode feature.

D.1.93 #timeBase-media

A TTML transformation processor supports the #timeBase-media feature if it recognizes and is capable of transforming the media value of the ttp:timeBase attribute.

A TTML presentation processor supports the #timeBase-media feature if it implements presentation semantic support for the media value of the ttp:timeBase attribute.

D.1.94 #timeBase-smpte

A TTML transformation processor supports the #timeBase-smpte feature if it recognizes and is capable of transforming the smpte value of the ttp:timeBase attribute and if it supports the #dropMode feature.

A TTML presentation processor supports the #timeBase-smpte feature if it implements presentation semantic support for the smpte value of the ttp:timeBase attribute and if it supports the #dropMode feature.

D.1.95 #timeContainer

A TTML transformation processor supports the #timeContainer feature if it recognizes and is capable of transforming the timeContainer attribute.

A TTML presentation processor supports the #timeContainer feature if it implements presentation semantic support for the timeContainer attribute.

D.1.96 #time-clock

A TTML transformation processor supports the #time-clock feature if it recognizes and is capable of transforming all values of the <timeExpression> that satisfy the following subset of time expression syntax:

<timeExpression>
  : hours ":" minutes ":" seconds ( fraction )?

A TTML presentation processor supports the #time-clock feature if it implements presentation semantic support for the same syntax specified above.

D.1.97 #time-clock-with-frames

A TTML transformation processor supports the #time-clock-with-frames feature if it supports the #frameRate, #frameRateMultiplier, and #subFrameRate features and if it recognizes and is capable of transforming all values of the <timeExpression> that satisfy the following subset of time expression syntax:

<timeExpression>
  : hours ":" minutes ":" seconds ( fraction | ":" frames ( "." sub-frames )? )?

A TTML presentation processor supports the #time-clock-with-frames feature if it implements presentation semantic support for the same features and syntax specified above.

D.1.98 #time-offset

A TTML transformation processor supports the #time-offset feature if it recognizes and is capable of transforming all values of the <timeExpression> that satisfy the following subset of time expression syntax:

<timeExpression>
  : time-count fraction? ( "h" | "m" | "s" | "ms" )

A TTML presentation processor supports the #time-offset feature if it implements presentation semantic support for the same syntax specified above.

D.1.99 #time-offset-with-frames

A TTML transformation processor supports the #time-offset-with-frames feature if it supports the #frameRate, #frameRateMultiplier, and #subFrameRate features and if it recognizes and is capable of transforming all values of the <timeExpression> that satisfy the following subset of time expression syntax:

<timeExpression>
  : time-count fraction? "f"

A TTML presentation processor supports the #time-offset-with-frames feature if it implements presentation semantic support for the same features and syntax specified above.

D.1.100 #time-offset-with-ticks

A TTML transformation processor supports the #time-offset-with-ticks feature if it supports the #tickRate feature and if it recognizes and is capable of transforming all values of the <timeExpression> that satisfy the following subset of time expression syntax:

<timeExpression>
  : time-count fraction? "t"

A TTML presentation processor supports the #time-offset-with-ticks feature if it implements presentation semantic support for the same features and syntax specified above.

D.1.101 #timing

A TTML transformation processor supports the #timing feature if it recognizes and is capable of transforming the following vocabulary defined by 10 Timing:

A TTML presentation processor supports the #timing feature if it implements presentation semantic support for the same vocabulary enumerated above.

D.1.102 #transformation

A TTML processor supports the #transformation feature if it (1) satisfies the generic processor criteria defined by 3.2.1 Generic Processor Conformance and (2) implements the transformation semantics of the following features:

D.1.103 #unicodeBidi

A TTML transformation processor supports the #unicodeBidi feature if it recognizes and is capable of transforming all defined values of the tts:unicodeBidi attribute.

A TTML presentation processor supports the #unicodeBidi feature if it implements presentation semantic support for all defined values of the tts:unicodeBidi attribute.

D.1.104 #visibility

A TTML transformation processor supports the #visibility feature if it recognizes and is capable of transforming all defined values of the tts:visibility attribute.

A TTML presentation processor supports the #visibility feature if it implements presentation semantic support for all defined values of the tts:visibility attribute.

D.1.105 #visibility-block

A TTML transformation processor supports the #visibility-block feature if it recognizes and is capable of transforming all defined values of the tts:visibility attribute when applied to a content element that would generate a block area during presentation processing.

A TTML presentation processor supports the #visibility-block feature if it implements presentation semantic support for all defined values of the tts:visibility attribute when applied to a content element that generates a block area.

D.1.106 #visibility-inline

A TTML transformation processor supports the #visibility-inline feature if it recognizes and is capable of transforming all defined values of the tts:visibility attribute when applied to a content element that would generate an inline area during presentation processing.

A TTML presentation processor supports the #visibility-inline feature if it implements presentation semantic support for all defined values of the tts:visibility attribute when applied to a content element that generates an inline area.

D.1.107 #visibility-region

A TTML transformation processor supports the #visibility-region feature if it recognizes and is capable of transforming all defined values of the tts:visibility attribute when applied to a region element.

A TTML presentation processor supports the #visibility-region feature if it implements presentation semantic support for all defined values of the tts:visibility attribute when applied to a region element.

D.1.108 #wrapOption

A TTML transformation processor supports the #wrapOption feature if it recognizes and is capable of transforming all defined values of the tts:wrapOption attribute.

A TTML presentation processor supports the #wrapOption feature if it implements presentation semantic support for all defined values of the tts:wrapOption attribute.

D.1.109 #writingMode

A TTML processor supports the #writingMode feature if it supports the following features:

D.1.110 #writingMode-vertical

A TTML transformation processor supports the #writingMode-vertical feature if it recognizes and is capable of transforming the tbrl, tblr, and tb values of the tts:writingMode attribute.

A TTML presentation processor supports the #writingMode-vertical feature if it implements presentation semantic support for the tbrl, tblr, and tb values of the tts:writingMode attribute.

D.1.111 #writingMode-horizontal

A TTML processor supports the #writingMode-horizontal feature if it supports the following features:

D.1.112 #writingMode-horizontal-lr

A TTML transformation processor supports the #writingMode-horizontal feature if it recognizes and is capable of transforming the lrtb and lr values of the tts:writingMode attribute.

A TTML presentation processor supports the #writingMode-horizontal-lr feature if it implements presentation semantic support for the lrtb and lr values of the tts:writingMode attribute.

D.1.113 #writingMode-horizontal-rl

A TTML transformation processor supports the #writingMode-horizontal feature if it recognizes and is capable of transforming the rltb and rl values of the tts:writingMode attribute.

A TTML presentation processor supports the #writingMode-horizontal-rl feature if it implements presentation semantic support for the rltb and rl values of the tts:writingMode attribute.

D.1.114 #zIndex

A TTML transformation processor supports the #zIndex feature if it recognizes and is capable of transforming the tts:zIndex attribute.

A TTML presentation processor supports the #zIndex feature if it implements presentation semantic support for the tts:zIndex attribute.

D.2 Feature Support

The following table, Table D-1 – Feature Support, enumerates every defined feature designation (expressed without the TT Feature Namespace), and, for each designated feature, specifies whether the feature must be implemented, i.e., is mandatory (M), or may be implemented, i.e., is optional (O), for transformation and presentation processors.

Table D-1 – Feature Support
FeatureTransformationPresentation
#animationOO
#backgroundColorOO
#backgroundColor-blockOO
#backgroundColor-inlineOO
#backgroundColor-regionOO
#bidiOO
#cellResolutionOO
#clockModeOO
#clockMode-gpsOO
#clockMode-localOO
#clockMode-utcOO
#colorOO
#contentMM
#coreMM
#directionOO
#displayOO
#display-blockOO
#display-inlineOO
#display-regionOO
#displayAlignOO
#dropModeOO
#dropMode-dropNTSCOO
#dropMode-dropPALOO
#dropMode-nonDropOO
#extentOO
#extent-regionOO
#extent-rootOO
#fontFamilyOO
#fontFamily-genericOO
#fontFamily-non-genericOO
#fontSizeOO
#fontSize-anamorphicOO
#fontSize-isomorphicOO
#fontStyleOO
#fontStyle-italicOO
#fontStyle-obliqueOO
#fontWeightOO
#fontWeight-boldOO
#frameRateOO
#frameRateMultiplierOO
#layoutOO
#lengthOO
#length-cellOO
#length-emOO
#length-integerOO
#length-negativeOO
#length-percentageOO
#length-pixelOO
#length-positiveOO
#length-realOO
#lineBreak-uax14OO
#lineHeightOO
#markerModeOO
#markerMode-continuousOO
#markerMode-discontinuousOO
#metadataOO
#nested-divOO
#nested-spanOO
#opacityOO
#originOO
#overflowOO
#overflow-visibleOO
#paddingOO
#padding-1OO
#padding-2OO
#padding-3OO
#padding-4OO
#pixelAspectRatioOO
#presentationOM
#profileMM
#showBackgroundOO
#structureMM
#stylingOO
#styling-chainedOO
#styling-inheritance-contentOO
#styling-inheritance-regionOO
#styling-inlineOO
#styling-nestedOO
#styling-referentialOO
#subFrameRateOO
#textAlignOO
#textAlign-absoluteOO
#textAlign-relativeOO
#textDecorationOO
#textDecoration-overOO
#textDecoration-throughOO
#textDecoration-underOO
#textOutlineOO
#textOutline-blurredOO
#textOutline-unblurredOO
#tickRateOO
#timeBase-clockOO
#timeBase-mediaOO
#timeBase-smpteOO
#timeContainerOO
#time-clockOO
#time-clock-with-framesOO
#time-offsetMM
#time-offset-with-framesOO
#time-offset-with-ticksOO
#timingMM
#transformationMO
#unicodeBidiOO
#visibilityOO
#visibility-blockOO
#visibility-inlineOO
#visibility-regionOO
#wrapOptionOO
#writingModeOO
#writingMode-verticalOO
#writingMode-horizontalOO
#writingMode-horizontal-lrOO
#writingMode-horizontal-rlOO
#zIndexOO

For the sake of convenience, the following table, Table D-2 – Mandatory Features - Transformation, enumerates all mandatory features for a TTML Transformation Processor, providing additional comments to summarize the context of usage or the nature of the feature. The Profile Definition Document that defines the corresponding DFXP Transformation Profile is specified in F.1 DFXP Transformation Profile.

Table D-2 – Mandatory Features - Transformation
FeatureComments
#content body, div, p, span, br
#core @xml:id, @xml:lang, @xml:space
#profile
#structure tt, head
#time-offset
#timing @begin, @dur, @end
#transformation

For the sake of convenience, the following table, Table D-3 – Mandatory Features - Presentation, enumerates all mandatory features for a TTML Presentation Processor, providing additional comments to summarize the context of usage or the nature of the feature. The Profile Definition Document that defines the corresponding DFXP Presentation Profile is specified in F.2 DFXP Presentation Profile.

Table D-3 – Mandatory Features - Presentation
FeatureComments
#content body, div, p, span, br
#core @xml:id, @xml:lang, @xml:space
#profile
#presentation
#structure tt, head
#time-offset
#timing @begin, @dur, @end

E Extensions

This appendix is normative.

This appendix specifies the syntactic form of extension designations, which are used to express authorial intent regarding the support for extension mechanisms in a TTML processor.

E.1 Extension Designations

An extension designation is expressed as a string that adheres to the following form:

extension-designation
  : extension-namespace designation

extension-namespace
  : TT Extension Namespace                  // http://www.w3.org/ns/ttml/extension/
  | Other Extension Namespace               // expressed as an absolute URI

designation
  : "#" token-char+

token-char
  : { XML NameChar }                        // XML 1.1 Production [4a]

If the extension namespace of an extension designation is the TT Extension Namespace, then all values of the following designation token are reserved for future standardization.

If the extension namespace of an extension designation is not the TT Extension Namespace, i.e., is an Other Extension Namespace, then the extension namespace must be expressed as an absolute URI capable of serving as a base URI used in combination with a designation token that takes the form of a fragment identifier.

F Profiles

This appendix is normative.

This appendix specifies the following standard TTML profiles:

The SDP US profile is defined in TTML Simple Delivery Profile for Closed Captions (US).

Each TTML profile is defined in terms of a Profile Definition Document, which is expressed as an XML document wherein the root element adheres to 6.1.1 ttp:profile.

F.1 DFXP Transformation Profile

The DFXP Transformation Profile is intended to be used to express minimum compliance for transformation processing.

<?xml version="1.0" encoding="utf-8"?>
<!-- this file defines the "dfxp-transformation" profile of ttml -->
<profile xmlns="http://www.w3.org/ns/ttml#parameter">
  <features xml:base="http://www.w3.org/ns/ttml/feature/">
    <!-- required (mandatory) feature support -->
    <feature value="required">#content</feature>
    <feature value="required">#core</feature>
    <feature value="required">#profile</feature>
    <feature value="required">#structure</feature>
    <feature value="required">#time-offset</feature>
    <feature value="required">#timing</feature>
    <feature value="required">#transformation</feature>
    <!-- optional (voluntary) feature support -->
    <feature value="optional">#animation</feature>
    <feature value="optional">#backgroundColor-block</feature>
    <feature value="optional">#backgroundColor-inline</feature>
    <feature value="optional">#backgroundColor-region</feature>
    <feature value="optional">#backgroundColor</feature>
    <feature value="optional">#bidi</feature>
    <feature value="optional">#cellResolution</feature>
    <feature value="optional">#clockMode-gps</feature>
    <feature value="optional">#clockMode-local</feature>
    <feature value="optional">#clockMode-utc</feature>
    <feature value="optional">#clockMode</feature>
    <feature value="optional">#color</feature>
    <feature value="optional">#direction</feature>
    <feature value="optional">#display-block</feature>
    <feature value="optional">#display-inline</feature>
    <feature value="optional">#display-region</feature>
    <feature value="optional">#display</feature>
    <feature value="optional">#displayAlign</feature>
    <feature value="optional">#dropMode-dropNTSC</feature>
    <feature value="optional">#dropMode-dropPAL</feature>
    <feature value="optional">#dropMode-nonDrop</feature>
    <feature value="optional">#dropMode</feature>
    <feature value="optional">#extent-region</feature>
    <feature value="optional">#extent-root</feature>
    <feature value="optional">#extent</feature>
    <feature value="optional">#fontFamily-generic</feature>
    <feature value="optional">#fontFamily-non-generic</feature>
    <feature value="optional">#fontFamily</feature>
    <feature value="optional">#fontSize-anamorphic</feature>
    <feature value="optional">#fontSize-isomorphic</feature>
    <feature value="optional">#fontSize</feature>
    <feature value="optional">#fontStyle-italic</feature>
    <feature value="optional">#fontStyle-oblique</feature>
    <feature value="optional">#fontStyle</feature>
    <feature value="optional">#fontWeight-bold</feature>
    <feature value="optional">#fontWeight</feature>
    <feature value="optional">#frameRate</feature>
    <feature value="optional">#frameRateMultiplier</feature>
    <feature value="optional">#layout</feature>
    <feature value="optional">#length-cell</feature>
    <feature value="optional">#length-em</feature>
    <feature value="optional">#length-integer</feature>
    <feature value="optional">#length-negative</feature>
    <feature value="optional">#length-percentage</feature>
    <feature value="optional">#length-pixel</feature>
    <feature value="optional">#length-positive</feature>
    <feature value="optional">#length-real</feature>
    <feature value="optional">#length</feature>
    <feature value="optional">#lineBreak-uax14</feature>
    <feature value="optional">#lineHeight</feature>
    <feature value="optional">#markerMode-continuous</feature>
    <feature value="optional">#markerMode-discontinuous</feature>
    <feature value="optional">#markerMode</feature>
    <feature value="optional">#metadata</feature>
    <feature value="optional">#nested-div</feature>
    <feature value="optional">#nested-span</feature>
    <feature value="optional">#opacity</feature>
    <feature value="optional">#origin</feature>
    <feature value="optional">#overflow-visible</feature>
    <feature value="optional">#overflow</feature>
    <feature value="optional">#padding-1</feature>
    <feature value="optional">#padding-2</feature>
    <feature value="optional">#padding-3</feature>
    <feature value="optional">#padding-4</feature>
    <feature value="optional">#padding</feature>
    <feature value="optional">#pixelAspectRatio</feature>
    <feature value="optional">#presentation</feature>
    <feature value="optional">#showBackground</feature>
    <feature value="optional">#styling-chained</feature>
    <feature value="optional">#styling-inheritance-content</feature>
    <feature value="optional">#styling-inheritance-region</feature>
    <feature value="optional">#styling-inline</feature>
    <feature value="optional">#styling-nested</feature>
    <feature value="optional">#styling-referential</feature>
    <feature value="optional">#styling</feature>
    <feature value="optional">#subFrameRate</feature>
    <feature value="optional">#textAlign-absolute</feature>
    <feature value="optional">#textAlign-relative</feature>
    <feature value="optional">#textAlign</feature>
    <feature value="optional">#textDecoration-over</feature>
    <feature value="optional">#textDecoration-through</feature>
    <feature value="optional">#textDecoration-under</feature>
    <feature value="optional">#textDecoration</feature>
    <feature value="optional">#textOutline-blurred</feature>
    <feature value="optional">#textOutline-unblurred</feature>
    <feature value="optional">#textOutline</feature>
    <feature value="optional">#tickRate</feature>
    <feature value="optional">#time-clock-with-frames</feature>
    <feature value="optional">#time-clock</feature>
    <feature value="optional">#time-offset-with-frames</feature>
    <feature value="optional">#time-offset-with-ticks</feature>
    <feature value="optional">#timeBase-clock</feature>
    <feature value="optional">#timeBase-media</feature>
    <feature value="optional">#timeBase-smpte</feature>
    <feature value="optional">#timeContainer</feature>
    <feature value="optional">#unicodeBidi</feature>
    <feature value="optional">#visibility-block</feature>
    <feature value="optional">#visibility-inline</feature>
    <feature value="optional">#visibility-region</feature>
    <feature value="optional">#visibility</feature>
    <feature value="optional">#wrapOption</feature>
    <feature value="optional">#writingMode-horizontal-lr</feature>
    <feature value="optional">#writingMode-horizontal-rl</feature>
    <feature value="optional">#writingMode-horizontal</feature>
    <feature value="optional">#writingMode-vertical</feature>
    <feature value="optional">#writingMode</feature>
    <feature value="optional">#zIndex</feature>
  </features>
  <extensions xml:base="http://www.w3.org/ns/ttml/extension/">
    <!-- required (mandatory) extension support -->
    <!-- optional (voluntary) extension support -->
  </extensions>
</profile>

F.2 DFXP Presentation Profile

The DFXP Presentation Profile is intended to be used to express minimum compliance for presentation processing.

<?xml version="1.0" encoding="utf-8"?>
<!-- this file defines the "dfxp-presentation" profile of ttml -->
<profile xmlns="http://www.w3.org/ns/ttml#parameter">
  <features xml:base="http://www.w3.org/ns/ttml/feature/">
    <!-- required (mandatory) feature support -->
    <feature value="required">#content</feature>
    <feature value="required">#core</feature>
    <feature value="required">#presentation</feature>
    <feature value="required">#profile</feature>
    <feature value="required">#structure</feature>
    <feature value="required">#time-offset</feature>
    <feature value="required">#timing</feature>
    <!-- optional (voluntary) feature support -->
    <feature value="optional">#animation</feature>
    <feature value="optional">#backgroundColor-block</feature>
    <feature value="optional">#backgroundColor-inline</feature>
    <feature value="optional">#backgroundColor-region</feature>
    <feature value="optional">#backgroundColor</feature>
    <feature value="optional">#bidi</feature>
    <feature value="optional">#cellResolution</feature>
    <feature value="optional">#clockMode-gps</feature>
    <feature value="optional">#clockMode-local</feature>
    <feature value="optional">#clockMode-utc</feature>
    <feature value="optional">#clockMode</feature>
    <feature value="optional">#color</feature>
    <feature value="optional">#direction</feature>
    <feature value="optional">#display-block</feature>
    <feature value="optional">#display-inline</feature>
    <feature value="optional">#display-region</feature>
    <feature value="optional">#display</feature>
    <feature value="optional">#displayAlign</feature>
    <feature value="optional">#dropMode-dropNTSC</feature>
    <feature value="optional">#dropMode-dropPAL</feature>
    <feature value="optional">#dropMode-nonDrop</feature>
    <feature value="optional">#dropMode</feature>
    <feature value="optional">#extent-region</feature>
    <feature value="optional">#extent-root</feature>
    <feature value="optional">#extent</feature>
    <feature value="optional">#fontFamily-generic</feature>
    <feature value="optional">#fontFamily-non-generic</feature>
    <feature value="optional">#fontFamily</feature>
    <feature value="optional">#fontSize-anamorphic</feature>
    <feature value="optional">#fontSize-isomorphic</feature>
    <feature value="optional">#fontSize</feature>
    <feature value="optional">#fontStyle-italic</feature>
    <feature value="optional">#fontStyle-oblique</feature>
    <feature value="optional">#fontStyle</feature>
    <feature value="optional">#fontWeight-bold</feature>
    <feature value="optional">#fontWeight</feature>
    <feature value="optional">#frameRate</feature>
    <feature value="optional">#frameRateMultiplier</feature>
    <feature value="optional">#layout</feature>
    <feature value="optional">#length-cell</feature>
    <feature value="optional">#length-em</feature>
    <feature value="optional">#length-integer</feature>
    <feature value="optional">#length-negative</feature>
    <feature value="optional">#length-percentage</feature>
    <feature value="optional">#length-pixel</feature>
    <feature value="optional">#length-positive</feature>
    <feature value="optional">#length-real</feature>
    <feature value="optional">#length</feature>
    <feature value="optional">#lineBreak-uax14</feature>
    <feature value="optional">#lineHeight</feature>
    <feature value="optional">#markerMode-continuous</feature>
    <feature value="optional">#markerMode-discontinuous</feature>
    <feature value="optional">#markerMode</feature>
    <feature value="optional">#metadata</feature>
    <feature value="optional">#nested-div</feature>
    <feature value="optional">#nested-span</feature>
    <feature value="optional">#opacity</feature>
    <feature value="optional">#origin</feature>
    <feature value="optional">#overflow-visible</feature>
    <feature value="optional">#overflow</feature>
    <feature value="optional">#padding-1</feature>
    <feature value="optional">#padding-2</feature>
    <feature value="optional">#padding-3</feature>
    <feature value="optional">#padding-4</feature>
    <feature value="optional">#padding</feature>
    <feature value="optional">#pixelAspectRatio</feature>
    <feature value="optional">#showBackground</feature>
    <feature value="optional">#styling-chained</feature>
    <feature value="optional">#styling-inheritance-content</feature>
    <feature value="optional">#styling-inheritance-region</feature>
    <feature value="optional">#styling-inline</feature>
    <feature value="optional">#styling-nested</feature>
    <feature value="optional">#styling-referential</feature>
    <feature value="optional">#styling</feature>
    <feature value="optional">#subFrameRate</feature>
    <feature value="optional">#textAlign-absolute</feature>
    <feature value="optional">#textAlign-relative</feature>
    <feature value="optional">#textAlign</feature>
    <feature value="optional">#textDecoration-over</feature>
    <feature value="optional">#textDecoration-through</feature>
    <feature value="optional">#textDecoration-under</feature>
    <feature value="optional">#textDecoration</feature>
    <feature value="optional">#textOutline-blurred</feature>
    <feature value="optional">#textOutline-unblurred</feature>
    <feature value="optional">#textOutline</feature>
    <feature value="optional">#tickRate</feature>
    <feature value="optional">#time-clock-with-frames</feature>
    <feature value="optional">#time-clock</feature>
    <feature value="optional">#time-offset-with-frames</feature>
    <feature value="optional">#time-offset-with-ticks</feature>
    <feature value="optional">#timeBase-clock</feature>
    <feature value="optional">#timeBase-media</feature>
    <feature value="optional">#timeBase-smpte</feature>
    <feature value="optional">#timeContainer</feature>
    <feature value="optional">#transformation</feature>
    <feature value="optional">#unicodeBidi</feature>
    <feature value="optional">#visibility-block</feature>
    <feature value="optional">#visibility-inline</feature>
    <feature value="optional">#visibility-region</feature>
    <feature value="optional">#visibility</feature>
    <feature value="optional">#wrapOption</feature>
    <feature value="optional">#writingMode-horizontal-lr</feature>
    <feature value="optional">#writingMode-horizontal-rl</feature>
    <feature value="optional">#writingMode-horizontal</feature>
    <feature value="optional">#writingMode-vertical</feature>
    <feature value="optional">#writingMode</feature>
    <feature value="optional">#zIndex</feature>
  </features>
  <extensions xml:base="http://www.w3.org/ns/ttml/extension/">
    <!-- required (mandatory) extension support -->
    <!-- optional (voluntary) extension support -->
  </extensions>
</profile>

F.3 DFXP Full Profile

The DFXP Full Profile is intended to be used to express maximum compliance for both transformation and presentation processing.

<?xml version="1.0" encoding="utf-8"?>
<!-- this file defines the "dfxp-full" profile of ttml -->
<profile xmlns="http://www.w3.org/ns/ttml#parameter">
  <features xml:base="http://www.w3.org/ns/ttml/feature/">
    <!-- required (mandatory) feature support -->
    <feature value="required">#animation</feature>
    <feature value="required">#backgroundColor-block</feature>
    <feature value="required">#backgroundColor-inline</feature>
    <feature value="required">#backgroundColor-region</feature>
    <feature value="required">#backgroundColor</feature>
    <feature value="required">#bidi</feature>
    <feature value="required">#cellResolution</feature>
    <feature value="required">#clockMode-gps</feature>
    <feature value="required">#clockMode-local</feature>
    <feature value="required">#clockMode-utc</feature>
    <feature value="required">#clockMode</feature>
    <feature value="required">#color</feature>
    <feature value="required">#content</feature>
    <feature value="required">#core</feature>
    <feature value="required">#direction</feature>
    <feature value="required">#display-block</feature>
    <feature value="required">#display-inline</feature>
    <feature value="required">#display-region</feature>
    <feature value="required">#display</feature>
    <feature value="required">#displayAlign</feature>
    <feature value="required">#dropMode-dropNTSC</feature>
    <feature value="required">#dropMode-dropPAL</feature>
    <feature value="required">#dropMode-nonDrop</feature>
    <feature value="required">#dropMode</feature>
    <feature value="required">#extent-region</feature>
    <feature value="required">#extent-root</feature>
    <feature value="required">#extent</feature>
    <feature value="required">#fontFamily-generic</feature>
    <feature value="required">#fontFamily-non-generic</feature>
    <feature value="required">#fontFamily</feature>
    <feature value="required">#fontSize-anamorphic</feature>
    <feature value="required">#fontSize-isomorphic</feature>
    <feature value="required">#fontSize</feature>
    <feature value="required">#fontStyle-italic</feature>
    <feature value="required">#fontStyle-oblique</feature>
    <feature value="required">#fontStyle</feature>
    <feature value="required">#fontWeight-bold</feature>
    <feature value="required">#fontWeight</feature>
    <feature value="required">#frameRate</feature>
    <feature value="required">#frameRateMultiplier</feature>
    <feature value="required">#layout</feature>
    <feature value="required">#length-cell</feature>
    <feature value="required">#length-em</feature>
    <feature value="required">#length-integer</feature>
    <feature value="required">#length-negative</feature>
    <feature value="required">#length-percentage</feature>
    <feature value="required">#length-pixel</feature>
    <feature value="required">#length-positive</feature>
    <feature value="required">#length-real</feature>
    <feature value="required">#length</feature>
    <feature value="required">#lineBreak-uax14</feature>
    <feature value="required">#lineHeight</feature>
    <feature value="required">#markerMode-continuous</feature>
    <feature value="required">#markerMode-discontinuous</feature>
    <feature value="required">#markerMode</feature>
    <feature value="required">#metadata</feature>
    <feature value="required">#nested-div</feature>
    <feature value="required">#nested-span</feature>
    <feature value="required">#opacity</feature>
    <feature value="required">#origin</feature>
    <feature value="required">#overflow-visible</feature>
    <feature value="required">#overflow</feature>
    <feature value="required">#padding-1</feature>
    <feature value="required">#padding-2</feature>
    <feature value="required">#padding-3</feature>
    <feature value="required">#padding-4</feature>
    <feature value="required">#padding</feature>
    <feature value="required">#pixelAspectRatio</feature>
    <feature value="required">#presentation</feature>
    <feature value="required">#profile</feature>
    <feature value="required">#showBackground</feature>
    <feature value="required">#structure</feature>
    <feature value="required">#styling-chained</feature>
    <feature value="required">#styling-inheritance-content</feature>
    <feature value="required">#styling-inheritance-region</feature>
    <feature value="required">#styling-inline</feature>
    <feature value="required">#styling-nested</feature>
    <feature value="required">#styling-referential</feature>
    <feature value="required">#styling</feature>
    <feature value="required">#subFrameRate</feature>
    <feature value="required">#textAlign-absolute</feature>
    <feature value="required">#textAlign-relative</feature>
    <feature value="required">#textAlign</feature>
    <feature value="required">#textDecoration-over</feature>
    <feature value="required">#textDecoration-through</feature>
    <feature value="required">#textDecoration-under</feature>
    <feature value="required">#textDecoration</feature>
    <feature value="required">#textOutline-blurred</feature>
    <feature value="required">#textOutline-unblurred</feature>
    <feature value="required">#textOutline</feature>
    <feature value="required">#tickRate</feature>
    <feature value="required">#time-clock-with-frames</feature>
    <feature value="required">#time-clock</feature>
    <feature value="required">#time-offset-with-frames</feature>
    <feature value="required">#time-offset-with-ticks</feature>
    <feature value="required">#time-offset</feature>
    <feature value="required">#timeBase-clock</feature>
    <feature value="required">#timeBase-media</feature>
    <feature value="required">#timeBase-smpte</feature>
    <feature value="required">#timeContainer</feature>
    <feature value="required">#timing</feature>
    <feature value="required">#transformation</feature>
    <feature value="required">#unicodeBidi</feature>
    <feature value="required">#visibility-block</feature>
    <feature value="required">#visibility-inline</feature>
    <feature value="required">#visibility-region</feature>
    <feature value="required">#visibility</feature>
    <feature value="required">#wrapOption</feature>
    <feature value="required">#writingMode-horizontal-lr</feature>
    <feature value="required">#writingMode-horizontal-rl</feature>
    <feature value="required">#writingMode-horizontal</feature>
    <feature value="required">#writingMode-vertical</feature>
    <feature value="required">#writingMode</feature>
    <feature value="required">#zIndex</feature>
    <!-- optional (voluntary) feature support -->
  </features>
  <extensions xml:base="http://www.w3.org/ns/ttml/extension/">
    <!-- required (mandatory) extension support -->
    <!-- optional (voluntary) extension support -->
  </extensions>
</profile>

G References

This appendix is normative.

CSS3 Color
Tantek Çelik and Chris Lilley, CSS Color Module Level 3, W3C Recommendation, 07 June 2011. (See http://www.w3.org/TR/2011/REC-css3-color-20110607/.)
GPS
Global Positioning System, US Naval Observatory. (See http://tycho.usno.navy.mil/gpsinfo.html.)
Media Types
Ned Freed and Nathaniel Borenstein, Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types, RFC 2046, November 1996, IETF.(See http://www.rfc-editor.org/rfc/rfc2046.txt.)
RELAX NG
ISO/IEC 19757-2, Information technology – Document Schema Definition Language (DSDL) – Part 2: Regular-grammar-based validation – RELAX NG, International Organization for Standardization (ISO).
SMIL 2.1
Dick Bultermann, et al., Synchronized Multimedia Integration Language (SMIL 2.1), W3C Recommendation, 13 December 2005. (See http://www.w3.org/TR/2005/REC-SMIL2-20051213/.)
SMPTE 12M
ANSI/SMPTE 12M, Television, Audio and Film – Time and Control Code, SMPTE Standard.
SRGB
IEC 61966-2-1, Multimedia systems and equipment – Colour measurement and management – Part 2-1: Colour management – Default RGB colour space – sRGB, International Electrotechnical Commission (IEC).
UAAG
Ian Jacobs, Jon Gunderson, and Eric Hansen, Eds., User Agent Accessibility Guidelines 1.0, W3C Recommendation, 17 December 2002. (See http://www.w3.org/TR/2002/REC-UAAG10-20021217/.)
UAX9
M. Davis, A. Lanin, and A. Glass, Unicode Bidirectional Algorithm, Unicode Consortium, 14 May 2017. (See http://www.unicode.org/reports/tr9/tr9-37.html.)
UAX14
Asmus Freytag, Line Breaking Properties, Unicode Consortium, 29 August 2005. (See http://www.unicode.org/reports/tr14/tr14-17.html.)
UTC
Recommendation TF.460, Standard-Frequency and Time-Signal Emissions, International Telecommunciations Union, Radio Sector (ITU-R).
WCAG
Ben Caldwell, et al., Eds., Web Content Accessibility Guidelines (WCAG) 2.0, W3C Recommendation, 11 December 2008. (See http://www.w3.org/TR/2008/REC-WCAG20-20081211/.)
XML 1.0
Tim Bray, et al. Extensible Markup Language (XML) 1.0 (Fifth Edition), W3C Recommendation, 26 November 2008. (See http://www.w3.org/TR/2008/REC-xml-20081126/.)
XML 1.1
Tim Bray, et al. Extensible Markup Language (XML) 1.1 (Second Edition), W3C Recommendation, 16 August 2006, edited in place 29 September 2006. (See http://www.w3.org/TR/2006/REC-xml11-20060816/.)
XML Base
Jonathan Marsh and Richard Tobin, Eds., XML Base (Second Edition), W3C Recommendation, 28 January 2009. (See http://www.w3.org/TR/2009/REC-xmlbase-20090128/.)
XML ID
Jonathan Marsh, Daniel Veillard, Norman Walsh, Eds., xml:id Version 1.0, W3C Recommendation, 09 September 2005. (See http://www.w3.org/TR/2005/REC-xml-id-20050909/.)
XML InfoSet
John Cowan and Richard Tobin, Eds., XML Information Set (Second Edition), W3C Recommendation, 04 February 2004. (See http://www.w3.org/TR/2004/REC-xml-infoset-20040204/.)
XML Media Types
Makato Murata, Simon St. Laurent, Kan Khon, Eds., XML Media Types, RFC 3023, January 2001, IETF.(See http://www.rfc-editor.org/rfc/rfc3023.txt.)
XML Namespaces 1.0
Tim Bray, et al. Namespaces in XML 1.0 (Third Edition), W3C Recommendation, 8 December 2009. (See http://www.w3.org/TR/2009/REC-xml-names-20091208/.)
XML Schema Part 1
Henry S. Thompson, David Beech, Murray Maloney, Noah Mendelsohn, Eds., XML Schema Part 1: Structures, W3C Recommendation, 28 October 2004. (See http://www.w3.org/TR/xmlschema-1/.)
XML Schema Part 2
Paul Biron and Ashok Malhotra, XML Schema Part 2: Datatypes, W3C Recommendation, 28 October 2004. (See http://www.w3.org/TR/xmlschema-2/.)
XSL 1.1
Anders Berglund, Extensible Stylesheet Language (XSL) Version 1.1, W3C Recommendation, 05 December 2006. (See http://www.w3.org/TR/2006/REC-xsl11-20061205/.)

H Other References (Non-Normative)

CC-DECODER-REQ
Closed Caption Decoder Requirements for Analog Television Receivers, United States Code of Federal Regulations, Title 47, Volume 1, Part 79, § 79.101. (See http://www.gpo.gov/fdsys/pkg/CFR-2012-title47-vol4/pdf/CFR-2012-title47-vol4-sec79-101.pdf.)
CEA-608-E
EIA/CEA-608-E, Line 21 Data Services, EIA/CEA Standard, Consumer Electronics Association (CEA).
CEA-708-E
CEA-708-E, Digital Television (DTV) Closed Captioning, CEA Standard, Consumer Electronics Association (CEA).
CSS2
Bert Bos et al., Cascading Style Sheets, Level 2 Revision 1, W3C Recommendation, 07 June 2011. (See http://www.w3.org/TR/2011/REC-CSS2-20110607/.)
MPEG DASH
ISO/IEC 23009-1, Information technology – Dynamic adaptive streaming over HTTP (DASH), International Organization for Standardization (ISO).
DCMES 1.1
Dublin Core Metadata Initiative, Dublin Core Metadata Element Set, Version 1.1: Reference Description. (See http://dublincore.org/documents/dces/.)
EBU-TT Live
EBU Tech3370, EBU-TT Part 3 Live Subtitling, European Broadcasting Union (EBU)
ISOBMFF
ISO/IEC 14496-30, Information technology – Coding of audio-visual objects – Part 30: Timed text and other visual overlays in ISO base media file format, International Organization for Standardization (ISO).
MPEG7-5
ISO/IEC 15938-5, Information technology – Multimedia content description interface – Part 5: Multimedia description schemes, International Organization for Standardization (ISO).
NSState
Norman Walsh, Ed., The Disposition of Names in an XML Namespace, TAG Finding, 9 January 2006. (See http://www.w3.org/2001/tag/doc/namespaceState-2006-01-09.)
QAF SG
Karl Dubost, et al., QA Framework: Specifications Guidelines, W3C Recommendation, 17 August 2005. (See http://www.w3.org/TR/qaframe-spec/.)
SMPTE 170M
ANSI/SMPTE 170M, Television – Composite Analog Video Signal – NTSC for Studio Applications, SMPTE Standard.
SMPTE 2052-11
SMPTE 2052-11, Conversion from CEA-708 Caption Data to SMPTE-TT, SMPTE Recommended Practice.
SVG 1.1
Jon Ferraiolo, Jun Fujisawa, Dean Jackson, Eds., Scalable Vector Graphics (SVG) 1.1 Specification, W3C Recommendation, 14 January 2003. (See http://www.w3.org/TR/2003/REC-SVG11-20030114/.)
TTAF1-REQ
Glenn Adams, Ed., Timed Text (TT) Authoring Format 1.0 Use Cases and Requirements, W3C Working Group Note, 27 April 2006. (See http://www.w3.org/TR/2006/NOTE-ttaf1-req-20060427/.)
TTML10
Glenn Adams, Ed., Timed Text Markup Language (TTML) 1.0, W3C Recommendation, 18 November 2010. (See http://www.w3.org/TR/2010/REC-ttaf1-dfxp-20101118/.)
XHTML 1.0
Steven Pemberton, et al., XHTML™ 1.0, The Extensible Hypertext Markup Language (Second Edition), W3C Recommendation, 01 August 2002. (See http://www.w3.org/TR/2002/REC-xhtml1-20020801/.)

I Requirements (Non-Normative)

The Timed Text Markup Language (TTML), also known as the Distribution Format Exchange Profile (DFXP) of the Timed Text Authoring Format (TTAF), satisfies a subset of the requirements established by [TTAF1-REQ]. The following table enumerates these requirements and indicates the extent to which they are satisfied by this specification, where S denotes a requirement is satisfied, P denotes a requirement is partially satisfied, and N denotes a requirement is not satisfied.

Table I-1 – Requirement Satisfaction
IDNameStatusComments
R100Specification FormatS
R101Specification ModularityS
R102Specification OrganizationS
R103Core and PeripherySTT extension namespaces
R104Evolution of CoreSTT extension namespaces
R105Ownership of CoreSTT namespaces
R106Surjection of CoreS
R107Evolution of PeripherySTT extension namespaces
R108Ownership of PeripherySNon-TT namespaces
R109TransformationSSupports 3GPP, QText, RealText, SAMI
R110Streamable TransformationSProgressive decoding
R111Accessibility – ContentSAlternative document instances
R112Accessibility – Authoring SystemS
R200AuthorabilityS
R201Multiple Natural LanguagesSAlternative document instances
R202Natural Language CoverageSUnicode 4.0
R203Natural Language Association GranularitySSee xml:lang
R204Minimum Character RepresentabilitySUnicode 4.0
R205Intrinsic and Extrinsic Text ContentPIntrinsic only
R206Markup AssociationPIntrinsic only
R207Conditional ContentN
R208Flowed TextS
R209Logical Flowed Text VocabularyS
R210Presentational Flowed Text VocabularySImplied mapping from logical flowed text.
R211Flowed Text Vocabulary RelationshipS
R212Flowed Text Vocabulary SeparationN
R213Non-Flowed TextN
R214Non-Flowed Text VocabularyN
R215Hybrid Flowed and Non-Flowed TextN
R216HyperlinkingNCan support via XLink
R217Embedded GraphicsN
R218Non-Embedded GraphicsN
R219Embedded FontsN
R220Non-Embedded FontsN
R221Descriptive VocabularySSee ttm:agent, ttm:role
R222Embedded AudioN
R223Non-Embedded AudioN
R290Markup FormatS
R291Markup Format and Unicode InteractionS
R292Extrinsic Resource ReferencesNNo extrinsic references
R293Schema Validity SpecificationS
R300Inline StylingS
R301Inline Styling FormPInline and referential styling
R301Out-of-Line StylingN
R301Out-of-Line Styling FormN
R304Styling PrioritizationS
R305Style Parameters – AuralN
R306Style Parameters – VisualPSupports absolute position, background color, color, display none, display alignment, font family, font size, font style, font weight, height, line height, origin, opacity, overflow, padding (before, after, start, end), text alignment, text shadow (as outline), visibility, width, writing mode, z-index
R390Style Parameter SymmetryS
R391Style Parameter DefinitionsS
R392Style Parameter ShorthandsS
R401Inline TimingS
R402Out-of-Line TimingN
R403Synchronization ParametersPSupports begin, end, dur
R404Synchronization Parameter Value SpacesPSupports offset values, media marker values (SMPTE 12M), wall-clock values
R405Time Containment SemanticsPSupports sequential, parallel
R500Animation ModesPSupports discrete
R502Highlight AnimationS<set tts:backgroundColor="..."/>
R503Fade Transition AnimationS<set tts:opacity="..."/>
R504Animated Style Parameters – AuralN
R505Animated Style Parameters – VisualPSupports animating background color, color, display, opacity, origin, visibility
N506Animated ContentS
R600Metadata Item AssociationSSee metadata, Metadata.class
R601Metadata Item ConstituentsPSupports name, value
R602Metadata Item Value RepresentationPSee metadata
R603Metadata Item ExtensibilitySSee metadata
R604Metadata Item ValidationSSee metadata
R690Dublin Core PreferenceNUses ttm:copyright, ttm:desc, ttm:title

J Vocabulary Derivation (Non-Normative)

This appendix provides information about the derivation of TTML vocabulary, separately describing derivation of elements and attributes.

J.1 Element Derivation

The first column of Table J-1 – Elements specifies a TTML element vocabulary item; the second column specifies the syntactic and/or semantic model on which the vocabulary item is based; the third column specifies the reference that defines the model (if a model is indicated); the fourth column specifies details about the derivation; the last column refers to additional notes describing the nature of the derivation.

In the fourth column, which describes details of derivation, a notation is use to indicate the addition or removal of an attribute. For example, in the derivation of the tt:div element, the details column includes "-@class", which denotes that the class attribute that is specified for use with the xhtml:div model element is not specified for use with the corresponding TTML element; in contrast, the details column includes "+@begin", which denotes that a begin attribute is added that is not specified for use with the xhtml:div model element.

Table J-1 – Elements
ElementModelReferenceDetailsNotes
tt:bodyxhtml:body[XHTML 1.0]-@class, -@dir, -@lang, -@on*, -@title; +@begin, +@dur, +@end, +@region, +@timeContainer, +@ttm:*, +@tts:*; content model subsetted to zero or more division (div) children, and supersetted by optional metadata and animation children1,2
tt:brxhtml:br[XHTML 1.0]-@class, -@title; +@ttm:*, +@tts:*, +@xml:lang, +@xml:space; content model supersetted by optional metadata and animation children for congruity with other content vocabulary1,2
tt:divxhtml:div[XHTML 1.0]-@class, -@dir, -@lang, -@on*, -@title; +@begin, +@dur, +@end, +@region, +@timeContainer, +@ttm:*, +@tts:*, +@xml:space; content model subsetted to zero or more paragraph (p) children, and supersetted by optional metadata and animation children1,2,3
tt:headxhtml:head[XHTML 1.0]-@dir, -@lang, -@profile; +@id, +@xml:space; content model changed to optional metadata children, followed by optional styling child, followed by optional layout child1,3
tt:layoutfo:simple-page-master[XSL 1.1]conceptual derivation4
tt:metadatasvg:metadata[SVG 1.1]-@xml:base; +@ttm:*, +@xml:lang, +@xml:space; content model subsetted to foreign namespace element content only (no #PCDATA)3,5
tt:pxhtml:p[XHTML 1.0]-@class, -@dir, -@lang, -@on*, -@title; +@begin, +@dur, +@end, +@region, +@timeContainer, +@ttm:*, +@tts:*, +@xml:space; content model subsetted to zero or more span children, and supersetted by optional metadata and animation children1,2,3
tt:regionfo:region-*[XSL 1.1]conceptual derivation4
tt:setsvg:set[SVG 1.1]-@* except begin, dur, end; +@tts:*, +@xml:lang, +@xml:space3,6
tt:spanxhtml:span[XHTML 1.0]-@class, -@dir, -@lang, -@on*, -@title; +@begin, +@dur, +@end, +@region, +@timeContainer, +@ttm:*, +@tts:*, +@xml:space; content model subsetted to zero or more #PCDATA or break (br) children, and supersetted by optional metadata and animation children1,2,3
tt:stylestyle specification[CSS2]XML representation of identified set of pairs of style property name and value, with optional inclusion of other styles by reference to other style elements7
tt:stylingxhtml:style[XHTML 1.0]XML representation of a set of style specifications sets, each represented by a style child element1,7
tt:ttxhtml:html[XHTML 1.0]-@dir, -@lang; +@id, +@ttp:*, +@xml:space; content model subsetted by permitting body and/or head to be optional1,8
ttm:actormpeg7:Creator[MPEG7-5]conceptual derivation4
ttm:agentmpeg7:Agent[MPEG7-5]conceptual derivation4
ttm:copyrightmpeg7:CopyrightString[MPEG7-5]conceptual derivation4
ttm:descsvg:desc[SVG 1.1]-@class, -@style, -@xml:base2,5,9
ttm:namempeg7:Name[MPEG7-5]conceptual derivation4
ttm:titlesvg:title[SVG 1.1]-@class, -@style, -@xml:base2,5,9
ttp:extension@requiredExtensions[SVG 1.1]conceptual derivation10
ttp:extensions@requiredExtensions[SVG 1.1]conceptual derivation10
ttp:feature@requiredFeatures[SVG 1.1]conceptual derivation10
ttp:features@requiredFeatures[SVG 1.1]conceptual derivation10
ttp:profile@baseProfile[SVG 1.1]conceptual derivation11

Note:

  1. Derivation is indicated with respect to the strict DTD defined by [XHTML 1.0], §A.1.

  2. The class attribute is effectively replaced by the style attribute, which, instead of specifying an inline style, refers indirectly to one or more style elements that define a set of style specification sets.

  3. The xml:lang and xml:space attributes are defined for all element types in order to support their inheritance semantics to operate in the context of foreign namespace elements.

  4. Derivation is conceptual (notional) only.

  5. The xml:base attribute is not used since there are no external references from core vocabulary.

  6. The attributeName and to attributes of svg:set are replaced by the direct expression of the target attribute name and value by use of a tts:* attribute.

  7. CSS style specification syntax is mapped to XML by use of attributes defined in the TT Style Namespace.

  8. The xml:id attribute is defined for use on all element types.

  9. The style attribute is supported only on Content elements.

  10. Derived from the use of @requiredExtensions and @requiredFeatures on the svg:svg element, but extended to support distinct specification of optionality.

  11. Derived from the use of @baseProfile and @version on the svg:svg element.

J.2 Attribute Derivation

The first column of Table J-2 – Attributes specifies a TTML attribute vocabulary item; the second column specifies the syntactic and/or semantic model on which the vocabulary item is based; the third column specifies the reference that defines the model (if a model is indicated); the fourth column specifies details about the derivation; the last column refers to additional notes describing the nature of the derivation.

In the fourth column, which describes details of derivation, a notation is use to indicate the addition or removal of an attribute value. For example, in the derivation of the timeContainer attribute, the details column includes "-excl", which denotes that the excl value that is specified for use with the timeContainer model attribute is not specified for use with the corresponding TTML attribute; similarly, an "+value" in the details column indicates that the attribute's values have been extended to include value.

Only those attributes that are specified for use on more than one TTML element type are listed below. Those per-element namespace attributes that are uniquely defined for a specific TTML element type are not listed below, but are considered to be part of the specific element type's derivation described in Table J-1 – Elements above.

Table J-2 – Attributes
AttributeModelReferenceDetailsNotes
beginbegin[SMIL 2.1]see notes2,3,4
durdur[SMIL 2.1]see notes2,3,4
endend[SMIL 2.1]see notes2,3,4
regionmaster-reference[XSL 1.1]conceptual derivation
styleclass[CSS2]dereferences style specification(s) directly
timeContainertimeContainer[SMIL 2.1]-excl, -none; no default attribute value5
ttm:agentnoneused to attribute agent of content
ttm:rolenoneused to attribute role of content
ttp:cellResolutionnoneexpresses uniform grid resolution for cell based coordinates
ttp:clockModenonedetermines how to interpret time expressions
ttp:frameRatenoneexpresses integral frame rate
ttp:frameRateMultipliernoneused to express non-integral, rational frame rates
ttp:markerModenoneexpresses marker continuity semantics
ttp:pixelAspectRationoneexpresses pixel aspect ratio of related media
ttp:profilenoneexpresses profile of TTML used by a Document Instance
ttp:dropModenoneexpresses frame counting (drop) modes
ttp:subFrameRatenoneexpresses sub-frame rate
ttp:tickRatenoneused to interpret tick based time expressions
ttp:timeBasenoneused to interpret semantics of time expressions
tts:backgroundColorbackground-color[XSL 1.1]-inherit1,6
tts:colorcolor[XSL 1.1]-inherit6
tts:directiondirection[XSL 1.1]-inherit
tts:displaydisplay[CSS2]only auto, none
tts:displayAligndisplay-align[XSL 1.1]-inherit1
tts:extentwidth, height[XSL 1.1]shorthand property
tts:fontFamilyfont-family[XSL 1.1]-inherit, extends generic family names1
tts:fontSizefont-size[XSL 1.1]-inherit1,7
tts:fontStylefont-style[XSL 1.1]-inherit, -backslant1
tts:fontWeightfont-weight[XSL 1.1]-inherit, -bolder, -lighter, -<number>1
tts:lineHeightline-height[XSL 1.1]-inherit, -<number>, -<space>1
tts:opacityopacity[CSS3 Color]-inherit
tts:origintop, left[XSL 1.1]shorthand property
tts:overflowoverflow[XSL 1.1]-inherit, -auto, -error-if-overflow
tts:paddingpadding[XSL 1.1]-inherit8
tts:showBackgroundshowBackground[SMIL 2.1]-inherit
tts:textAligntext-align[XSL 1.1]-inherit1
tts:textDecorationtext-decoration[XSL 1.1]-inherit1,9,12
tts:textOutlinetext-shadow[XSL 1.1]-inherit10,12
tts:unicodeBidiunicode-bidi[XSL 1.1]-inherit1
tts:visibilityvisibility[XSL 1.1]-inherit, -collapse
tts:wrapOptionwrap-option[XSL 1.1]-inherit1
tts:writingModewriting-mode[XSL 1.1]-inherit, +tblr1
tts:zIndexz-index[XSL 1.1]-inherit1
xml:idxml:id[XML ID]complies with model
xml:langxml:lang[XML 1.0]complies with model
xml:spacexml:space[XML 1.0]see notes11

Note:

  1. Attribute name and/or value(s) are normalized to use lowerCamelCase naming convention.

  2. Restricted to expressing a clock value that denotes one of the following in accordance to whether the parameter expressed by the ttp:timeBase attribute is media, smpte, or clock, respectively: (1) an offset from an implicit syncbase that is linked to a media time line, (2) an event time that represents the occurrence of an implicit media marker, or (3) a wall-clock time.

  3. Syntactically subsets and supersets the [SMIL 2.1] Clock-value syntax as follows: (1) requires non-negative Full-clock-value or Timecount-value; (2) if Full-clock-value then hours must be two or more digits; (3) if Timecount-value, then metric must be specified; (4) uses m as alias for min metric to denote minutes; (5) adds f and t metrics denoting frames and ticks, respectively; (6) adds alternative expression of optional Fraction in Full-clock-value by specifying frame count or frame count with subframe count.

  4. Interpretation of time expression is further constrained by parameters expressed by ttp:clockMode, ttp:dropMode, ttp:frameRate, ttp:frameRateMultiplier, ttp:markerMode, ttp:subFrameRate, ttp:tickRate, and ttp:timeBase attributes.

  5. Uses subset of named colors from model to which two aliases are added as follows: magenta as fuchsia, and cyan as aqua.

  6. If not specified, then parallel (par) container semantics apply to the element types specified by 10.2.4 timeContainer.

  7. Restricts size to length specification which can be a percentage; adds optional second length (or percentage) for specifying separate horizontal and vertical scaling of glyph's EM square.

  8. Expressed in terms of writing mode relative padding properties rather than absolute padding properties.

  9. Excludes blink and no-blink values.

  10. Uses only one length specification instead of two, where one length defines distance of outline effect from nominal edge of glyph contour outline perpendicular to point of glyph contour. Percentage lengths are also added to express outline effect in relative to font size. Outline effects are intended to be drawn both outside of outer closed contours and inside of inner closed contours.

  11. On root element, default attribute value specified as default, which is defined in terms of whitespace normalization. Semantics of preservation and default normalization are defined in terms of presentation semantics by 7.2.3 xml:space.

  12. Defined to be inheritable.

K QA Framework Compliance (Non-Normative)

This appendix specifies the compliance of this specification with the requirements and guidelines defined by QA Framework Specifications Guidelines [QAF SG].

K.2 Guidelines

Table K-2 – QA Framework Guidelines Checklist
GuidelineYESNON/ANotes
Good Practice 01: Define the specification's conformance model in the conformance clause.YES
Good Practice 02: Specify in the conformance clause how to distinguish normative from informative content.YES
Good Practice 03: Provide the wording for conformance claims.YES
Good Practice 04: Provide an Implementation Conformance Statement Pro Forma.NO
Good Practice 05: Require an Implementation Conformance Statement as part of valid conformance claims.YES
Good Practice 06: Provide examples, use cases, and graphics.YES
Good Practice 07: Write sample code or tests.YES
Good Practice 08: When imposing requirements by normative references, address conformance dependencies.YES1
Good Practice 09: Define unfamiliar terms in-line and consolidate the definitions in a glossary section.YES
Good Practice 10: Use terms already defined without changing their definition.YES2
Good Practice 11: Use formal languages when possible.YES
Good Practice 12: Write Test Assertions.NO3
Good Practice 13: Create subdivisions of the technology when warranted.YES
Good Practice 14: If the technology is profiled, define rules for creating new profiles.YES
Good Practice 15:Use optional features as warranted.YES
Good Practice 16: Clearly identify optional features.YES
Good Practice 17: Indicate any limitations or constraints on optional features.YES
Good Practice 18: If extensibility is allowed, define an extension mechanism.YES
Good Practice 19: Warn extension creators to create extensions that do not interfere with conformance.YES
Good Practice 20: Define error-handling for unknown extensions.YES4
Good Practice 21: Explain how to avoid using a deprecated feature.N/A5
Good Practice 22: Identify obsolete features.N/A5
Good Practice 23: Define an error handling mechanism.YES

Note:

  1. When making normative references to external specifications, specific clauses or sections are cited.

  2. See also J Vocabulary Derivation.

  3. Test assertions and test suites will be provided prior to entering Proposed Recommendation (PR) phase.

  4. See criterion #3 in 3.2 Processor Conformance and definition of TTML Abstract Document Instance.

  5. No feature is deprecated or obsoleted by this version of this specification.

L Streaming TTML Content (Non-Normative)

TTML Content can be authored to meet the following characteristics that may be useful in streaming scenarios:

L.1 Root and Branch Fragmentation

One possible means by which TTML Content may be streamed is to partition a Document Instance's information set into non-overlapping fragments, where one particular fragment, call it the root fragment, represents the front matter (head) of the Document Instance as well as its top level structural elements, and other fragments represent content whose time intervals are expected to be active in parallel.

In applications that require arbitrary (random) entry into a stream, i.e., the property of being able to start reading data at an arbitrary data access unit, the root fragment will be repetitively transmitted (inserted) into the stream in order to permit a decoder to resynchronize and acquire sufficient structural information in the information set in order to interpret subsequent content fragments.

An example of such a fragmentation of a Document Instance is shown in Figure 3 – Fragment Streaming.

Figure 3 – Fragment Streaming
Fragment Streaming

Note:

This specification does not define a transport buffer model or a decoder capabilities model.

L.2 Temporal Fragmentation

Another means by which TTML Content may be streamed is to partition a Document Instance's information set into temporally bound fragments, each of which is itself a document instance that contains all the front matter (head) and content required to present it, where the temporal interval for each fragment is constrained, either by the Document Interchange Context or by the Document Processing Context or by both, such that temporal overlaps with other fragments are resolved.

For example, some document processing contexts resolve temporal overlap by specifying that a maximum of one document instance can be active at any moment in the timeline, and additionally specify precedence rules to establish which document instance that is, in case there are multiple candidates.

In order to ensure that all the content is correctly displayed, any content that falls into an Intermediate Synchronic Document (ISD) whose interval overlaps with more than one fragmentation interval might need to be duplicated within each fragment that is required to generate that ISD. It is possible for implementations to identify adjacent ISDs that are identical except in their intervals and replace them with a single ISD covering the combined interval.

The intent of this approach is that presentation processors are able to generate an equivalent sequence of ISDs to that which would be generated by a non-streamed version of the document instance, while taking advantage of the ability to avoid duplicating some controllable amount of front matter, by varying the segment duration. Reconstruction of the original source is not guaranteed to result in an identical document instance.

Note:

This technique is used for example in [ISOBMFF] and in [EBU-TT Live].

An example of such a fragmentation of a Document Instance is shown in Figure 4 – Temporal fragmentation.

Figure 4 – Temporal fragmentation
Temporal Fragment Streaming

Note:

In the above example, a single document instance has content visible during intervals T1 through T6 and is fragmented into two document instances (segments), the first including all content and referenced styles and regions required during T1 through T3, the second including all content and referenced styles and regions required during T4 through T6.

M Concrete Encoding (Non-Normative)

In the absence of other requirements, it is recommended that a Document Instance be concretely encoded as a well-formed XML 1.0 [XML 1.0] document using the UTF-8 character encoding.

Note:

When using XML 1.0 [XML 1.0] as the concrete encoding of TTML, only the following named character entities are defined: &amp;, &lt;, and &gt;.

N Time Expression Semantics (Non-Normative)

This appendix describes the intended semantics for interpreting time expressions in Document Instances.

Note:

It is expected that the information in this appendix will be elevated to normative status in a future revision of this specification.

Note:

The phrase local real time as used below is intended to model a virtual real time clock in the document processing context, where local means in the immediate proximity of the implementation of this processing context. The intent of defining relationships with this virtual clock is to establish a locally valid physical realization of time for didactic purposes.

Note:

The phrase play rate as used below is intended to model a (possibly variable) parameter in the document processing context wherein the rate of playback (or interpretation) of time may artificially dilated or narrowed, for example, when slowing down or speeding up the rate of playback of a Related Media Object. Without loss of generality, the following discussion assumes a fixed play(back) rate. In the case of variable play rates, appropriate adjustments may need to be made to the resulting computations.

The Document Processing Context defines the applicable epoch and any epoch-related offsets to be used when establishing the Synthetic Document Syncbase.

N.1 Clock Time Base

When operating with the clock time base, the following semantics should be applied for interpreting time expressions, as defined by <timeExpression>, and their relationship to media time and local real time.

The clock time base C is related to local real time R expressed in the epoch E (defined by the Document Processing Context) as follows:

TTML Semantics – Clock Time and Real Time Relationship


R = C + epochOffset + discontinuityOffset

where C ∈ ℜ, 0 ≤ C < ∞, C in seconds since the most immediately prior midnight of the reference clock base;

epochOffset ∈ ℜ, 0 ≤ epochOffset < ∞, epochOffset in seconds, with 0 being the beginning of epoch E, and where the value of epochOffset is determined from the computed value of the ttp:clockMode parameter as follows:

(1) if local, then the difference between the local real time at the most immediately prior local midnight and the local real time at the beginning of epoch E, expressed in seconds;

(2) if gps, then the difference between the GPS time at the most immediately prior GPS midnight and the GPS time at the beginning of epoch E, expressed in seconds;

(3) if utc, then the difference between the UTC time at the most immediately prior UTC midnight and the UTC time at the beginning of epoch E, expressed in seconds;

discontinuityOffset ∈ ℜ, −∞ < discontinuityOffset < ∞, discontinuityOffset in seconds, and where the value of discontinuityOffset is equal to the sum of leap seconds (and fractions thereof) that have been added (or subtracted) since the most immediately prior midnight in the reference clock base;

and epochOffset and discontinuityOffset are determined once and only once prior to the beginning of the Root Temporal Extent such that during the period between value determination and the beginning of the Root Temporal Extent there occurs no local midnight or reference clock base discontinuity.

Time value expressions, as denoted by a <timeExpression>, are related to clock time C as follows:

TTML Semantics – Time Expressions and Clock Time Relationship


If a time expression uses the clock-time form or an offset-time form that doesn't use the ticks (t) metric, then:

C = 3600 * hours + 60 * minutes + seconds

where hours, minutes, seconds components are extracted from time expression if present, or zero if not present. Furthermore, a fraction component, if present, is added to the seconds component to form a real-valued seconds component.

Otherwise, if a time expression uses an offset-time form that uses the ticks (t) metric, then:

C = ticks / tickRate

Note:

The frames and sub-frames terms and the frames (f) metric of time expressions do not apply when using the clock time base.

The clock time base C is independent of media time M:

TTML Semantics – Clock Time and Media Time Relationship


M ¬∝ C

Note:

That is to say, timing is disconnected from (not necessarily proportional to) media time when the clock time base is used. For example, if the media play rate is zero (0), media playback is suspended; however, timing coordinates will continue to advance according to the natural progression of clock time in direct proportion to the reference clock base. Furthermore, if the media play rate changes during playback, presentation timing is not affected.

N.2 Media Time Base

When operating with the media time base, the following semantics should be applied for interpreting time expressions, as defined by <timeExpression>, and their relationship to media time, document time, and local real time.

N.2.1 Relationship to Local Real Time

The media time base M is related to local real time R expressed in the epoch E (defined by the Document Processing Context) as follows:

TTML Semantics – Media Time and Real Time Relationship


R = playRate * M + epochOffset

where M ∈ ℜ, 0 ≤ M < ∞, M in seconds, with 0 corresponding to the beginning of the Root Temporal Extent;

playRate ∈ ℜ, −∞ < playRate < ∞, playRate is unit-less, and where the value of playRate is determined by the document processing context;

and epochOffset ∈ ℜ, 0 ≤ epochOffset < ∞, epochOffset in seconds, with 0 corresponding to the beginning of an epoch E, and where the value of epochOffset is the difference between the local real time at the beginning of the Root Temporal Extent and the local real time at the the beginning of epoch E, expressed in seconds.

N.2.2 Relationship to Media Time

Time value expressions, as denoted by a <timeExpression>, are related to media time M in accordance to the ttp:frameRate, ttp:subFrameRate, and ttp:frameRateMultiplier parameters as follows:

TTML Semantics – Time Expressions and Media Time Relationship


If a time expression uses a clock-time form or an offset-time form that doesn't use the ticks (t) metric, then:

M = referenceBegin + 3600 * hours + 60 * minutes + seconds + ((frames + (subFrames / subFrameRate)) / effectiveFrameRate)

where referenceBegin is determined according to whether the nearest ancestor time container employs parallel (par) or sequential (seq) semantics: if parallel or if sequential and no prior sibling timed element exists, then referenceBegin is the media time that corresponds to the beginning of the nearest ancestor time container or zero (0) if this time container is the Root Temporal Extent; otherwise, if sequential and a prior sibling timed element exists, then referenceBegin is the media time that corresponds to the active end of the immediate prior sibling timed element;

the hours, minutes, seconds, frames, subFrames components are extracted from time expression if present, or zero if not present; furthermore, if the time expression takes the form of a clock-time expression, then the fraction component, if present, is added to the seconds component to form a real-valued seconds component, or, if the time expression takes the form of an offset-time expression, then the fraction component, if present, is added to the time-count component to form a real-valued time-count component according to the specified offset metric;

subFrameRate is the computed value of the ttp:subFrameRate parameter;

and effectiveFrameRate (in frames per second) is frameRate * frameRateMultiplier where frameRate is the computed value of the ttp:frameRate parameter and frameRateMultiplier is the computed value of the ttp:frameRateMultiplier parameter.

Otherwise, if a time expression uses an offset-time form that uses the ticks (t) metric, then:

M = referenceBegin + ticks / tickRate

where referenceBegin is as described above;

the ticks component is extracted from time expression;

and tickRate is the computed value of the ttp:tickRate parameter;

Note:

If the computed frameRateMultiplier ratio is not integral, then effectiveFrameRate will be a non-integral rational.

Note:

The above formalisms assumes that the Root Temporal Extent corresponds with the beginning of a related media object. If this assumption doesn't hold, then an additional offset that accounts for the difference may be introduced when computing media time M.

N.2.3 Relationship to Document Time

The computed document times are used as the equivalent media times with no offset.

Note:

Any additional media time processing imposed by e.g. a wrapper format is out of scope of the TTML specification.

For example [ISOBMFF] and [MPEG DASH] provide mechanisms for wrapping TTML documents as samples or segments and defining the offset of their media timelines relative to other media such as audio or video.

The following document fragments are equivalent in timing:

Example Fragment – 1
<tt ttp:timeBase="media" ...>
...
<body>
   <div xml:id="d1" begin="1s">
      <p xml:id="p1" begin="0s" end="1s">First paragraph</p>
      <p xml:id="p2" begin="2s" end="3s">Second paragraph</p>
   </div>
</body>
</tt>

Example Fragment – 2
<tt ttp:timeBase="media" ...>
...
<body>
   <div xml:id="d1">
      <p xml:id="p1" begin="1s" end="2s">First paragraph</p>
      <p xml:id="p2" begin="3s" end="4s">Second paragraph</p>
   </div>
</body>
</tt>

Timing diagram showing the mapping of document times to media times in the absence of other external information.
Media time
In this example, using the the terminology of [SMIL 2.1], the implicit duration of the body element is identical to its computed duration which is also the Root Temporal Extent.

However if the Document Processing Context specifies a range of applicable media times, those limit the resolved begin and end times and therefore the Root Temporal Extent.

In the following example the processing context defines that the media time range over which the document is active is from 1.5s to 3.5s, and this defines the Root Temporal Extent since timed content is present at both of those times.

Timing diagram showing the mapping of document times to media times when the media time range is constrained by the processing context.
Media time
The grey background indicates the periods when the Document Processing Context defines the document to be inactive.
If the document processing context were to define that the media time range is 0-3s then the Root Temporal Extent would be from 1s to 2s as defined by p1 and p2 would never be shown.

N.3 SMPTE Time Base

When operating with the smpte time base, the following semantics should be applied for interpreting time expressions, as defined by <timeExpression>, and their relationship to media time and local real time.

If the computed value of the ttp:markerMode parameter is discontinuous, then there is no direct relationship between time expressions and media time M or local real time R. In this case, time expressions refer to synchronization events (markers) emitted by the Document Processing Context when SMPTE Time Codes are encountered in the Related Media Object.

Otherwise, if the computed value of the ttp:markerMode parameter is continuous, then the relationships between time expressions and local real time and media time are as described below in terms of a Synthetic SMPTE Document Syncbase, here referred to as the SMPTE time base S.

TTML Semantics – Time Expressions and SMPTE Time Relationship


S = (countedFrames - droppedFrames + (subFrames / subFrameRate)) / effectiveFrameRate

where

countedFrames = (3600 * hours + 60 * minutes + seconds) * frameRate + frames

hours, minutes, seconds, frames, subFrames components are extracted from time expression if present, or zero if not present;

droppedFrames is computed as follows:

1. let dropMode be the computed value of the ttp:dropMode parameter;

2. if dropMode is dropNTSC, let droppedFrames = (hours * 54 + floor(minutes - minutes/10)) * 2;

3. otherwise, if dropMode is dropPAL, let droppedFrames = (hours * 27 + floor(minutes/2 - minutes/20)) * 4;

4. otherwise, let droppedFrames = 0;

frameRate is the computed value of the ttp:frameRate parameter;

subFrameRate is the computed value of the ttp:subFrameRate parameter;

and effectiveFrameRate (in frames per second) is frameRate * frameRateMultiplier where frameRate is the computed value of the ttp:frameRate parameter and frameRateMultiplier is the computed value of the ttp:frameRateMultiplier parameter.

Notwithstanding the above, if a time expression contains a frame code that is designated as dropped according to 6.2.3 ttp:dropMode, then that time expression should be considered to be invalid for purposes of validation assessment.

The SMPTE time base S is related to the media time base M as follows:

TTML Semantics – SMPTE Time and Media Time Relationship


M = referenceBegin + S

where referenceBegin is determined according to whether the nearest ancestor time container employs parallel (par) or sequential (seq) semantics: if parallel or if sequential and no prior sibling timed element exists, then referenceBegin is the SMPTE time that corresponds to the beginning of the nearest ancestor time container or zero (0) if this time container is the Root Temporal Extent; otherwise, if sequential and a prior sibling timed element exists, then referenceBegin is the SMPTE time that corresponds to the active end of the immediate prior sibling timed element;

Given the derived media time base as described above, then media time base M is related to the local real time R as described in N.2 Media Time Base above.

O Common Caption Style Examples (Non-Normative)

This section provides examples of the following common caption styles using TTML Content to obtain the desired behavior:

O.1 Pop-On Caption Example

An example of paint-on captions. In this example, two regions are targeted with alternating, paint-on content, where content is timed using explicit sequential time containment rules. Each paragraph is non-overlapping in time and appears in the same single row of its targeted region.

Example – Pop-On Captions
<tt ttp:cellResolution="60 20" xml:lang="en" xmlns="http://www.w3.org/ns/ttml"
  xmlns:ttp="http://www.w3.org/ns/ttml#parameter" xmlns:tts="http://www.w3.org/ns/ttml#styling">
  <head>
    <layout>
      <region xml:id="r1" tts:color="white" tts:origin="10c 4c" tts:extent="40c 1c"/>
      <region xml:id="r2" tts:color="yellow" tts:origin="10c 8c" tts:extent="40c 1c"/>
    </layout>
  </head>
  <body>
    <div timeContainer="seq">
      <p region="r1" dur="4s">Lorem ipsum dolor sit</p>
      <p region="r2" dur="4s">Amet consectetur adipiscing elit</p>
      <p region="r1" dur="6s">Sed do eiusmod tempor incididunt labore</p>
      <p region="r2" dur="4s">et dolore magna aliqua</p>
      <p region="r1" dur="7s">Ut enim ad minim veniam quis, nostrud</p>
    </div>
  </body>
</tt>

O.2 Roll-Up Caption Example

An example of roll-up captions. Roll-up effects are achieved by using overlapped time intervals, where zero, one, or two paragraphs appear in the region at a given time. Each paragraph consumes a single row (line) of the region since no wrapping occurs. Depending on whether a presentation processor supports smooth scrolling between adjacent synchronic intermediate document instances, the transitions, i.e., moving an old paragraph (line) out and a new paragraph (line) in, will be either smooth or discrete.

Example – Roll-Up Captions
<tt ttp:cellResolution="60 20" xml:lang="en" xmlns="http://www.w3.org/ns/ttml"
  xmlns:ttp="http://www.w3.org/ns/ttml#parameter" xmlns:tts="http://www.w3.org/ns/ttml#styling">
  <head>
    <layout>
      <region xml:id="r1" tts:color="white" tts:origin="10c 4c" tts:extent="40c 2c" tts:displayAlign="after"/>
    </layout>
  </head>
  <body>
    <div region="r1">
      <p begin="0s" end="8s">Lorem ipsum dolor sit</p>
      <p begin="4s" end="12s">Amet consectetur adipiscing elit</p>
      <p begin="8s" end="18s">Sed do eiusmod tempor incididunt labore</p>
      <p begin="14s" end="25s">et dolore magna aliqua</p>
      <p begin="18s" end="29s">Ut enim ad minim veniam quis, nostrud</p>
    </div>
  </body>
</tt>

O.3 Paint-On Caption Example

An example of paint-on captions. Paint-on effects are achieved by using timed span elements in order to expose (paint) inline text units, e.g., words, over some time interval. Here, five paragraphs have their individual words sequentially timed in order to paint one new word every second. The end of the active duration of each inline element coincides with the end of the div element's parallel time container, so that once a word is painted, it remains in the region (on its rendered line) until the div element's active time interval lapses.

Example – Paint-On Captions
<tt ttp:cellResolution="60 20" xml:lang="en" xmlns="http://www.w3.org/ns/ttml"
  xmlns:ttp="http://www.w3.org/ns/ttml#parameter" xmlns:tts="http://www.w3.org/ns/ttml#styling">
  <head>
    <layout>
      <region xml:id="r1" tts:color="white" tts:origin="10c 4c" tts:extent="40c 5c" tts:displayAlign="after"/>
    </layout>
  </head>
  <body>
    <div region="r1" begin="0s" end="25s">
      <p>
        <span begin="0s">Lorem</span>
        <span begin="1s">ipsum</span>
        <span begin="2s">dolor</span>
        <span begin="3s">sit</span>
      </p>
      <p>
        <span begin="4s">Amet</span>                
        <span begin="5s">consectetur</span>
        <span begin="6s">adipiscing</span>
        <span begin="7s">elit</span>
      </p>
      <p>
        <span begin="8s">Sed</span>
        <span begin="9s">do</span>
        <span begin="10s">eiusmod</span>
        <span begin="11s">tempor</span>
        <span begin="12s">incididunt </span>
        <span begin="13s">labore</span>
     </p>
     <p>
        <span begin="14s">et</span>
        <span begin="15s">dolore</span>
        <span begin="16s">magna</span>
        <span begin="17s">aliqua</span>
      </p>
      <p>
        <span begin="18s">Ut</span>
        <span begin="19s">enim</span>
        <span begin="20s">ad</span>
        <span begin="21s">minim</span>
        <span begin="22s">veniam</span>
        <span begin="23s">quis,</span>
        <span begin="24s">nostrud</span>
      </p>
    </div>
  </body>
</tt>

P Acknowledgments (Non-Normative)

The editor acknowledges the current and former members of the Timed Text Working Group, the members of other W3C Working Groups, and industry experts in other forums who have contributed directly or indirectly to the process or content of this document as follows:

Glenn Adams, Thomas Bause-Mason, John Birch, Kees Blom, Bert Bos, Brad Botkin, Dick Bulterman, Frans de Jong, Mike Dolan, Martin Dürst, Donald Evans, Geoff Freed, Al Gilman, Giles Godart-Brown, Markus Gylling, Markku Hakkinen, Sean Hayes, Erik Hodge, Philipp Hoschka, Suzi Hyun, Michael Jordan, Masahiko Kaneko, Courtney Kennedy, George Kerscher, David Kirby, Andrew Kirkpatrick, Philippe Le Hégaret, Pierre-Anthony Lemieux, Chris Lilley, Jason Livingston, Monica Martin, Matthew May, Nigel Megitt, Thierry Michel, Frank Olivier, Soohong Daniel Park, Silvia Pfeiffer, Brian Raymor, David Ronca, Patrick Schmitz, David Singer, Craig Smithpeters, Andreas Tai, and Mohamed Zergaoui.

The editor wishes to especially acknowledge the following contributions by members: Micheal Dolan (SMPTE time codes, streaming; SMPTE liaison), David Kirby (introductory example document; SMPTE time codes, descriptive metadata; EBU/AAF liaison), Geoff Freed (styling and example images of style properties), Sean Hayes (advanced profile concepts, including applicative timing), Eric Hodge (timing), Thierry Michel (metadata), and Dave Singer (animation, scrolling).

The Working Group dedicates this specification to our colleague David Kirby.