This document describes and prioritises gaps for the support of languages using the Bengali script on the Web and in eBooks. In particular, it is concerned with text layout. It checks that needed features are supported in W3C specifications, in particular HTML and CSS and those relating to digital publications. It also checks whether the features have been implemented in browsers and ereaders. This is a preliminary analysis.
This document describes and prioritises gaps for the support of languages using the Bengali script on the Web and in eBooks. In particular, it is concerned with text layout. It checks that needed features are supported in W3C specifications, in particular HTML and CSS and those relating to digital publications. It also checks whether the features have been implemented in browsers and ereaders. This document linked to from the language matrix that tracks Web support for many languages.
The editor's draft of this document is being developed by the India International Program Task Force, 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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The W3C needs to make sure that the text layout and typographic needs of scripts and languages around the world are built in to technologies such as HTML, CSS, SVG, etc. so that Web pages and eBooks can look and behave as people expect around the world.
This page documents issues for languages using the Bengali script, including Bangla, Assamese, and Manipuri, in terms of support by specifications or user agents (browsers, e-readers, etc.).
A summary of this report and others can be found as part of the language matrix.
This version of the document is a preliminary analysis
Gap analysis work usually starts with a preliminary analysis, conducted quickly by one or a small group of experts. Then a more detailed analysis is carried out, involving a wider range of experts. The detailed analysis may involve the development of tests, in order to illustrate issues and track results for browsers. The next phase is ongoing maintenance. It is expected that the resulting document will not be frozen: as gaps are fixed, this should be noted in the document. It is also possible that new gaps are noticed or arise, and they can be added to this document when that happens.
As the gap analysis develops, the requirements for features that are problematic should be described in the companion document, Text Layout Requirements for the Bengali Script. Links to the appropriate part of that document should be added to this document as the material is created. Note that the requirements document should not contain any technology-specific information: all of that belongs here.
This document not only describes gaps, it also attempts to prioritise them in terms of the impact on the local user. The prioritisation is indicated by colour.
It is important to note that these colours do not indicate to what extent a particular features is broken. They indicate the impact of a broken or missing feature on the content author or end user.
Basic styling is the level that would be generally accepted as sufficient for most Web pages. Advanced level support would include additional features one might expect to include in ebooks or other advanced typographic formats. There may be features of a script or language that are not supported on the Web, but that are not generally regarded as necessary (usually archaic or obscure features). In this case, the feature can be described here, but the status should be marked as OK.
The decision as to what priority level is assigned to a described gap is down to the experts doing the gap analysis. It may not always be straightforward to decide. If a given section in this document refers to more than one feature that is broken, each with different impacts on Web users, the priority for the section should be the lowest denominator.
A cell can be scored as OK if the feature in question is specified in an appropriate specification, and is supported by user agents. A specification that is in CR or later and has two implementations in 'major' browsers will count. This means that the feature may not be supported in all browsers yet. (At some point in the future we may try to distinguish, visually, whether support is available in a specification but still pending in major browsers or applications.)
See also General page layout & progression for features such as column layout, page turning direction, etc. that are affected by text direction.
Are the script requirements for vertically oriented text met? What about if you mix vertical text with scripts that are normally only horizontal? Do you need a switch to use different characters in vertical vs. horizontal text? Does the browser support short runs of horizontal text in vertical lines (tate-chu-yoko in Japanese) as expected? Is the orientation of characters and the directional ordering of characters supported as needed? See available information or check for currently needed data.
Upright characters in vertical lines of text don't break correctly, due to the problem of detecting syllable boundaries correctly mentioned above. Marking this as basic, since this is not a common use case.
See requirements at: Indic Layout Requirements
If this script runs right-to-left, are there any issues when handling that? Is bidirectional text adequately supported? What about numbers and expressions? Do the Unicode bidi controls and HTML markup provide the support needed? Is isolation of directional runs problematic? See available information or check for currently needed data.
Are there any character repertoire issues preventing use of this script on the Web? Do variation selectors need attention? Are there any other encoding-related issues?
Do the standard fallback fonts used in browsers (eg. serif, sans-serif, cursive, etc.) match expectations? Are special font or OpenType features needed for this script that are not available? See available information or check for currently needed data.
This covers ways of modifying the glyphs, such as for italicisation, bolding, oblique, etc. Do italic fonts lean in the right direction? Is synthesised italicisation problematic? Are there other problems relating to bolding or italicisation - perhaps relating to generalised assumptions of applicability? See available information or check for currently needed data.
Does the script in question require additional user control features to support alterations to the position or shape of glyphs, for example adjusting the distance between the base text and diacritics, or changing the glyphs used in a systematic way? Do you need to be able to compose/decompose conjuncts, or show characters that are otherwise hidden, etc? See available information or check for currently needed data.
If this script is cursive (eg. Arabic, N'Ko, Syriac, etc), are there problems or needed features related to the handling of cursive text? Do cursive links break if parts of a word are marked up or styled? Do Unicode joiner and non-joiner characters behave as expected? See available information or check for currently needed data.
Does your script need special text transforms that are not supported? Does your script convert letters to uppercase, capitalised and lowercase alternatives according to your typographic needs? Do you need to to convert between half-width and full-width presentation forms? See available information or check for currently needed data.
This is about how text is divided into graphemes, words, sentences, etc., and behaviour associated with that. Do Unicode grapheme clusters appropriately segment character units for your script? When you double- or triple-click on the text, is the expected range of characters highlighted? When you move through the text with the cursor, or backspace, etc. do you see the expected behaviour? (Some of the answers to these questions may be picker up in other sections, such as line-breaking, or initial-letter styling.) See available information or check for currently needed data.
The Unicode concept of 'grapheme cluster' currently fails to represent syllabic conjuncts (plus vowels, etc) in scripts like Bengali. Bengali is even more complex in this regards because it requires Ya-Phalaa after vowel which is formed by Vowel followed by Viaram(Hasant) and consonant combination, therefore breaking the basic notion of Akshar formation to represent the glyph(Ya-Phalaa/Ja-Phalaa). This means that various editing operations, line breaking algorithms, vertical text, etc. are likely to break text at the wrong point.
Indic Layout Requirements provides a grammar for indian orthographic syllable boundaries which works for Bengali, and CSS uses the concept of 'typographic character unit', rather than grapheme cluster, in its specs with the explanation that these cases are beyond the scope of the grapheme cluster concept and that implementations should provide appropriate support. In addition, a modification to the concept of grapheme cluster is currently in development at the Unicode Consortium, which is likely to resolve the problem for a script like Bengali.
See requirements at: Indic Layout Requirements
Bengali uses Devanagari phrase separator । U+0964 DEVANAGARI DANDA (called DanRi in Bengali) to represent the end of the sentence. Bengali also uses U+0965 DEVANAGARI DOUBLE DANDA (called DuiDanRi in Bengali) and as per the Unicode recommendation, both have to come from Devanagari block of Unicode. Devanagari phrase separator । U+0964 DEVANAGARI DANDA or ॥ U+0965 DEVANAGARI DOUBLE DANDA are encoded in the DEVANAGARI block with the intent that they should be used as common punctuation for all the major scripts of India including Bengali.
The properties of Danda and Double Danda should be the same as the properties of FullStop or other punctuation marks, and a new line should not begin with Danda and Double Danda.
If you put a span around the ব first character of the two character syllable বি in বিভাগের (eg. in order to color or otherwise style it), the vowel-sign no longer appears at the start of the word, but looks like incorrect inputting at the wrong place.
Apparently this requirement is a bit difficult to cater to as it requires the knowledge to be transferred by the font to the rendering engine about which part of the glyph is attributed to which code-point in storage. However, if it can be achieved, nothing like it.
This is about ways of marking text (see also specific sections dedicated to quotations and inline notes/annotations). Is it possible to express emphasis or highlight content as expected? Bold, italic and under-/over-lines are not always appropriate, and some scripts have their own unique ways of doing things, that are not in the Western tradition at all. Text delimiters mark certain items or sections off from the main text, such as book names in Chinese, quotations, head markers in Tibetan, etc, and often involve the use of punctuation. Is there any behaviour that isn't well supported, such as overlines for numeric digits in Syriac? Are there issues about the positioning or use of underlines? Some aspects related to the drawing of lines alongside or through text involve local typographic considerations. Do underlines need to be broken in special ways for this script? Do you need support for additional line shapes or widths? Does the distance or position of the lines relative to the text need to vary in ways that are not achievable? Are lines correctly drawn relative to vertical text? See available information or check for currently needed data.
Indian language text has some signs called as Matras which sometimes join above the shirorekha or below the normal baseline.
Applications should ensure that the underline and overline when getting rendered, should adequately be taken into consideration. Chrome browser seemed to be perfectly rendering the underline and overline feature by breaking the same where a matra occurs. Internet Explorer also handles it a bit differently by appropriately lowering or heightening the respective lines.
Are there any issues when dealing with quotations marks, especially when nested? Should block quotes be indented or handled specially? See available information or check for currently needed data.
html tag sets the language of a page, the HTML specification says that the
q element should by default produce quotation marks according to the information in CLDR for that language.
For Bangla and Assamese, (Manipuri is not listed), CLDR says that the default quote marks should be, reading right to left, “...”, and embedded quote marks ‘...’. Edge fails to produce any quotation marks, although it does so for other languages. (Firefox, Chrome & Safari are ok.) See a test and results.
In addition, the default quotation marks for the
q element are not set to the appropriate characters by the browser when the element appears inside a Bangla/Assamese section of a page that has a different overall language. This is currently per the HTML specification (both W3C and WhatWG). There is an issue raised against the WhatWG version for this to be changed.
Bangla/Assamese quotes embedded in text in another language can also be problematic if the outer language uses different quotation marks. This is due to the browsers choosing default quotation marks based on the language of the quotation, rather than that of the surrounding text. See a test. This behaviour is specified in the WhatWG version of the HTML spec, but no longer in the W3C version. There is an issue raised against the WhatWG version for this to be changed.
Marking all the above as advanced, because use of the
q element is optional (quote characters can be used instead), and it can be styled using CSS for the general case.
The ruby spec currently specifies an initial subset of requirements for fine-tuning the typography of phonetic and semantic annotations of East Asian text, including furigana, pinyin and zhuyin fuhao systems. Is is adequate for what it sets out to do? What other controls will be needed in the future? What about other types of inline annotation, such as warichu? (For referent-type notes such as footnotes, see below.) See available information or check for currently needed data.
If the script has its own set of number digits, are there any issues in how they are used? Does the script or language use special format patterns that are problematic (eg. 12,34,000 in India)? What about date/time formats and selection - and are non-Gregorian calendars needed? Do percent signs and other symbols associated with number work correctly, and do numbers need special decorations, (like in Ethiopic or Syriac)? See available information or check for currently needed data.
Both ASCII and Bengali Numerals are used in Bengali. Most of the user community identifies with both. However, mono-lingual (mono-script rather) readers may want a fully localized web page including numbers, date, time and calendar to name a few.
Does the script have special ways of representing inline notes (such as kumimoji in Japanese) or other inline features that need to be supported? See available information or check for currently needed data.
Does the browser capture the rules about the way text in your script wraps when it hits the end of a line? Does line-breaking wrap whole 'words' at a time, or characters, or something else (such as syllables in Tibetan and Javanese)? What characters should not appear at the end or start of a line, and what should be done to prevent that? See available information or check for currently needed data.
Is hyphenation used for your script, or something else? If hyphenation is used, does it work as expected? (Note, this is about line-end hyphenation when text is wrapped, rather than use of the hyphen and related characters as punctuation marks.) See available information or check for currently needed data.
When text in a paragraph needs to have flush lines down both sides, does it follow the rules for your script? Does the script need assistance to conform to a grid pattern? Does your script allow punctuation to hang outside the text box at the start or end of a line? Where adjustments are need to make a line flush, how is that done? Do you shrink/stretch space between words and/or letters? Are word baselines stretched, as in Arabic? What about paragraph indents, or the need for logical alignment keywords, such as start/end, rather than left/right? See available information or check for currently needed data.
Some scripts create emphasis or other effects by spacing out the words, letters or syllables in a word. Are there requirements for this script/language that are unsupported? (For justification related spacing, see below.) See available information or check for currently needed data.
For various reasons wherever a word needs to be broken in constituent characters in case of Latin script, Indian language words can and should be broken based on Akshara.
As the W3C specification points to Unicode Text Segmentation (TR 29), it is observed that some of the browsers support it (e.g. Chrome and Firefox) whereas Microsoft Edge and Interner Explorer seems to break the words in individual characters.
It has been marked as basic as the Unicode Text Segmentation rules themselves need to be matured enough to cater to nuances of many languages that get written using Bangala script.
There are two instances in Bengali where hasant(virama) is preceded by a full vowel (U+0985 অ - BENGALI LETTER A and U+098F এ - BENGALI LETTER E). For rendering Ya-Phalaa(Ja-Phalaa) followed by অ and এ , it is necessary to type U+09CD hasant(virama) plus U+09AF ja preceded by the said vowels. This is a purely ligatural entity and the addition of Ya-Phalaa and ā matra is used to elicit the /æ/ sound as in English 'application', 'administration' etc. The Brahmi script, by nature does not have halant after a vowel. Halant is ‘vowel killer’. Only the consonants have inherent halants. Bengali has a deviant feature in the orthography here where ligatures অ্যা and এ্যা call for a combination of halant after a vowel. Also, in Bengali there are some conjunct using ZWJ and ZWJ which can be problematic..
Also, in cases where there is wrong Akshara formation e.g. Consonant+Matra+Matra, the breaking seems to stack ill formed akshara into one set instead of clearly breaking it separate. This breaking behaviour needs to improve.
The CSS Counter Styles specification describes a limited set of simple and complex styles for counters to be used in list numbering, chapter heading numbering, etc.The rules plus more counter styles (totalling around 120 for over 30 scripts) are listed in the document Ready-made Counter Styles. Do these cover your needs? Are the details correct? Are there other aspects related to counters and lists that need to be addressed? See available information or check for currently needed data.
Bengali CSS counter style is defined in the document Ready-made Counter Styles. Same is also defined in the CSS Counter Styles specification, the other relies on the user-defined mechanism specified in that spec in order to be applied.
Does the browser or ereader correctly handle special styling of the initial letter of a line or paragraph, such as for drop caps or similar? How about the size relationship between the large letter and the lines alongide? where does the large letter anchor relative to the lines alongside? is it normal to include initial quote marks in the large letter? is the large letter really a syllable? etc. Are all of these things working as expected? .See available information or check for currently needed data.
Because of the problems associated with grapheme cluster boundaries (see above), first-letter selection in CSS doesn't work well for conjuncts. For example, chrome fails to style the whole conjunct in ব্রাউজার when using ::first-letter in a selector, and styles only the ব্ instead of ব্রা. Similar is the case of Internet Explorer, it only styles ব. This is problematic for many words in a script such as Bengali, and forces the content author to use explicit spans rather than the proper mechanism for selecting initial letter.
CSS uses the concept of 'typographic character unit', rather than grapheme cluster, in its specs with the explanation that these cases are beyond the scope of the grapheme cluster concept and that implementations should provide appropriate support. In addition, a modification to the concept of grapheme cluster is currently in development at the Unicode Consortium, which is likely to resolve the problem for a script like Bengali.
In addition, the alignment of styled initial-letter character glyphs with the rest of the text is not clearly specified or implemented.
See requirements at: Indic Layout Requirements
Does the browser support requirements for baseline alignment between mixed scripts and in general? See available information or check for currently needed data.
By and large, Indian scripts in browsers are rendered with default fonts provided by back-end Operating Systems. If there are major differences in physical size for a particular font size, which most of the times are, it shows the mixed-script text in an un-organized way. This obviously affects all the base-line attributes.
In your script, is the first line of text typically indented at the start of a paragraph? Are there other features of paragraph design that are peculiar to your script? See available information or check for currently needed data.
How are the main text area and ancilliary areas positioned and defined? Are there any special requirements here, such as dimensions in characters for the Japanese kihon hanmen? The book cover for scripts that are read right-to-left scripts is on the right of the spine, rather than the left. Is that provided for? When content can flow vertically and to the left or right, how do you specify the location of objects, text, etc. relative to the flow? For example, keywords 'left' and 'right' are likely to need to be reversed for pages written in English and page written in Arabic. Do tables and grid layouts work as expected? How do columns work in vertical text? Can you mix block of vertical and horizontal text correctly? Does text scroll in the expected direction? See available information or check for currently needed data.
Does your script have special requirements for notes, footnotes, endnotes or other necessary annotations of this kind in the way needed for your culture? (There is a section above for purely inline annotations, such as ruby or warichu. This section is more about annotation systems that separate the reference marks and the content of the notes.) See available information or check for currently needed data.
Are there special conventions for page numbering, or the way that running headers and the like are handled? See available information or check for currently needed data.
Are vertical form controls well supported? In right-to-left scripts, is it possible to set the base direction for a form field? Is the scroll bar on the correct side? etc. See available information or check for currently needed data.
Some cultures define text areas and page progression direction very differently from those in the West (eg. kihon hanmen in Japanese). Is this an issue for you? Are widows and orphans relevant? If pages progress RTL, are there issues for support with paged media? What about things such as cross-references, bookmarks, columns, printer marks, tables of contents and indexes? See available information or check for currently needed data.
Sometimes a script or language does things that are not common outside of its sphere of influence. This is a loose bag of additional items that weren't previously mentioned. This section may also be relevant for observations related to locale formats (such as number, date, currency, format support).
There are many other CSS modules which may need review for script-specific requirements, not to mention the SVG, HTML, Speech, MathML and other specifications. What else is likely to cause problems for worldwide deployment of the Web, and what requirements need to be addressed to make the Web function well locally?