This document describes or points to requirements for the layout and presentation of Urdu text when it is used by Web standards and technologies, such as HTML, CSS, Mobile Web, Digital Publications, and Unicode.

This document describes the basic requirements for Urdu layout and text support on the Web and in eBooks. These requirements provide information for Web technologies such as CSS, HTML and digital publications about how to support users of Arabic scripts.

The editor's draft of this document is being developed as part of the Arabic script enablement initiative, part of the W3C Internationalization Interest Group. It is published by the Internationalization Working Group. The end target for this document is a Working Group Note.

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Introduction

The aim of this document is to describe the basic requirements for Urdu layout and text support on the Web and in eBooks. These requirements provide information for Web technologies such as CSS, HTML and digital publications, and for application developers, about how to support users of Urdu.

Contributors

The initial information in this document was created by Richard Ishida (W3C).

See also the GitHub contributors list for the Arabic Script Enablement project, and the discussions.

About this document

The aim of this document is to describe the basic requirements for Urdu layout and text support on the Web and in eBooks. These requirements provide information for Web technologies such as CSS, HTML and digital publications, and for application developers, about how to support users of Urdu.

The document focuses on typographic layout issues. For a deeper understanding of the Urdu orthography and how it works see Urdu (Nastaliq Arabic) Orthography Notes, which includes topics such as: Phonology, Vowels, Consonants, Encoding choices, and Numbers.

Other related resources

To complement any content authored specifically for this document, the sections in the document also point to related, external information, tests, GitHub discussions, etc.

The Language enablement index points to this document and others, and provides a central location for developers and implementers to find information related to various scripts.

The W3C also has a repository with discussion threads related to the Arabic script, including requests from developers to the user community for information about how scripts/languages work, and a notification system that tracks issues in W3C working groups related to Arabic scripts. See a list of unresolved questions for Arabic script experts. Each section below points to related discussions. See also the repository home page.

All topics

Text direction

Bidirectional text

Arabic script is written from right to left. Numbers, even Arabic numbers, are written from left to right, as is text in a script that is normally left-to-right.

When the main script is Arabic, the layout and structure of pages and documents are also set from right to left.

Vertical text

Glyph shaping & positioning

Fonts & font styles

Context-based shaping & positioning

Cursive text

Arabic script is a cursive writing system; i.e, letters can join to their neighboring letters. Besides the core behavior of the script, there are some details on how content is encoded in Unicode, and some rules around joining behavior when rendering special cases.

Letterform slopes, weights, & italics

Typographic units

Characters & encoding

Grapheme/word segmentation & selection

Punctuation & inline features

Phrase & section boundaries

Quotations & citations

Emphasis & highlighting

Abbreviation, ellipsis & repetition

Inline notes & annotations

Text decoration & other inline features

Data formats & numbers

Line & paragraph layout

Line breaking & hyphenation

Text alignment & justification

Text spacing

Baselines, line height, etc.

Arabic script ascenders and descenders extend much further than those of the Latin script, and care must be taken to correctly align text in the different scripts when they appear together.

Lists, counters, etc.

Styling initials

Page & book layout

Footnotes, endnotes, etc