Adlam Gap Analysis

W3C Group Draft Note

More details about this document
This version:
https://www.w3.org/TR/2023/DNOTE-adlm-gap-20231004/
Latest published version:
https://www.w3.org/TR/adlm-gap/
Latest editor's draft:
https://w3c.github.io/afrlreq/gap-analysis/adlm-gap
History:
https://www.w3.org/standards/history/adlm-gap/
Commit history
Editor:
(W3C)
Feedback:
GitHub w3c/afrlreq (pull requests, new issue, open issues)

Copyright © 2020-2023 World Wide Web Consortium. W3C® liability, trademark and permissive document license rules apply.

Abstract

This document describes and prioritises gaps for the support of Adlam 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.

Status of This Document

This section describes the status of this document at the time of its publication. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at https://www.w3.org/TR/.

This document describes and prioritises gaps for the support of Adlam 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. It is linked to from the language matrix that tracks Web support for many languages.

This document is an individual contribution, and is not currently a work item in any group, however, you can contact the Internationalization Working Group for more information. We welcome contributions to this and/or other documents.

This document was published by the Internationalization Working Group as a Group Draft Note using the Note track.

Group Draft Notes are not endorsed by W3C nor its Members.

This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

The W3C Patent Policy does not carry any licensing requirements or commitments on this document.

This document is governed by the 12 June 2023 W3C Process Document.

1. Introduction

The W3C needs to make sure that the 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 difficulties people encounter when trying to use the Pular language with the Adlam script on the Web.

Having identified an issue, it investigates the current status with regards to web specifications and implementations by user agents (browsers, e-readers, etc.), and attempts to prioritise the severity of the issue for web users.

See an overview of the Adlam script and its use for the Pular language. (Not a W3C document.)

A summary of this report and others can be found as part of the language matrix.

1.1 Work flow

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.

1.2 Prioritization

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.

Key:

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.)

2. Text direction

See also General page layout & progression for features such as column layout, page turning direction, etc. that are affected by text direction.

2.1 Vertical text

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.

#11 Vertical text in spines, etc.

GitHub issue #11

This issue is applicable to most languages.

Vertical text may occur for special effects (the spine of a book, table column headings, etc). Typographically, it is simply horizontal text that is rotated. There is no way to do this effectively until browsers support the new CSS properties.

For more details, see this GitHub issue, which is being used to track this gap. Please add any discussion there, and not to this issue.

2.2 Bidirectional text

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.

#23 :dir lacks wide support

GitHub issue #23

This issue is applicable to all languages with RTL orthographies.

Style sheets need to add special rules for RTL styles if they are not supported by logical properties or values.

One approach is to create a second style sheet which, when pulled into an HTML page, overrides styles in the main style sheet with settings for RTL text. This approach is not ideal because it requires maintaining the styles in two separate locations, which can therefore get out of synch, and it requires explicit addition of a call to the second style sheet in every page that will support RTL text.

The :dir() pseudo-class avoids these issues by allowing the content author to include the RTL variations in the same style sheet as the others. However, it is not yet supported by all major browser engines.

For more details, see this GitHub issue, which is being used to track this gap. Please add any discussion there, and not to this issue.

#16 Need support for dirname attribute

GitHub issue #16

This issue is common to all RTL scripts.

When strings are passed around, some applications don't receive or use information about the appropriate base direction to use for those strings when they are rendered as part of a page.

This can lead to text being incorrectly aligned, and to text within a sentence or paragraph being incorrectly ordered. Some of this can be addressed by using heuristics to detect the direction first-strongly directional character in the string, but some strings can fail such heuristics.

HTML's dirname attribute, which is supposed to pass information with form data about direction of the text isn't fully interoperable across major browser engines.

FIXED !
This gap is now fixed. For details, see this GitHub issue.

#13 Webkit doesn't automatically right-align Adlam

GitHub issue #13

Adlam text displayed in a block element with dir set to auto should be automatically right-aligned, unless the base direction is set to LTR, like this:

Screenshot 2021-01-22 at 15 33 38

The GAP
In WebKit the text appears as follows:

Screenshot 2021-01-22 at 15 36 02

This is a serious issue, and indicates that first-strong heuristics are not being applied. Note that this was not an issue for N'Ko, Arabic, Hebrew, Thaana, or Syriac text.

Tests & results
Interactive test, Text in languages that use RTL scripts will be automatically aligned with the right side of their container when dir is set to auto

  • Gecko: ✅ *Browser: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:96.0) Gecko/20100101 Firefox/96.0*
  • Blink: ✅ *Browser: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/97.0.4692.71 Safari/537.36*
  • Webkit: ✅ Adlam used to be broken, but is now fixed (see the bug report). *Browser: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/15.2 Safari/605.1.15*

Action taken
Webkit

Outcomes
This was fixed in WebKit, so it now works as expected for all 3 major browser engines.

Priority
Priority initially set to basic because this was a serious issue for Adlam users, but now set to OK.

#10 Support for isolating formatting characters lacking in some browsers

GitHub issue #10

This issue is common to all RTL scripts.

For support of bidirectional text in plain text, the Unicode Standard provides a number of formatting characters, which include RLI, LRI, PDI and FSI. See an explanation of how these work.

Note that the Unicode Standard recommends the use of RLI/LRI...PDI rather than the former RLE/LRE...PDF, because the newer code points directionally isolate the text they surround from that around it. This is important for producing bidirectional text. Although markup should be used most of the time in HTML pages, there are parts of an HTML document that don't support markup, such as the title element and title, alt, and other attributes. These characters can be necessary for managing inline runs of such text.

The Gap:
The RLI, LRI, FSI, PDI characters still don't produce the necessary behaviour in all major web browser engines.

Gecko and Blink support these characters. Webkit doesn't.

Spec status:
This is an issue related to Unicode support, rather than W3C specs.

html mentions that text content may contain these characters.

Tests & results:
i18n test suite, Isolating formatting characters

Action taken:
Webkit (2014)

Outcomes:
WebKit now supports the required behaviour for these formatting characters. This means that they can be used interoperably on all major web browsers.

Priority
These characters control fundamental behaviours for support of RTL scripts so priority is set as Basic.

#8 Logical CSS keyword support needed

GitHub issue #8

This issue is common to all RTL scripts.

Adoption of logical keywords such as -start and -end, rather than -left and -right needs to be completed.

For margins, padding, block size, border colour, width & style, logical keywords such as margin-inline-start or margin-block-end are widely supported by major browsers in their simplest forms (such as those just mentioned). However, logical properties are not well supported in shorthands such as margin-block or margin-inline or the margin property. The lack of support for shorthands is significant, since they are expected to have high use.

For more details, see this GitHub issue, which is being used to track this gap. Please add any discussion there, and not to this issue.

3. Characters and phrases

3.1 Characters & encoding

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? See available information or check for currently needed data.

#41 OK

GitHub issue #41

Adlam has no issues for this topic.

3.2 Fonts

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.

#19 Glyphs for characters in other blocks incorrectly falling back to system font

GitHub issue #19

This issue is applicable to Adlam and N'Ko.

When text contains a punctuation mark such as an Arabic question mark, the glyph displayed should be that contained in the Adlam or N'Ko font, if it contains one.

The Gap:
At least one browser on desktop and mobile render the Arabic question mark (and perhaps other punctuation) using a fallback font despite the font containing the appropriate glyph.

Example in N'Ko:

Incorrect question mark glyph

This was tested with the Noto Sans NKo font. In Gecko and Blink the question mark falls back to a different font.

It may be related to a script itemization issue where Adlam or N'Ko is not properly recognized. A request was made to the Unicode Consortium to fix the Script Extensions table.

Other characters from the Arabic and Devanagari script blocks exhibit the same behaviour. For example, a danda used in Limbu, or a tatweel used in Syriac.

More:

Tests & results:

Action taken:
Gecko

Outcomes
The Unicode Consortium has fixed the script extensions table.

Gecko is implementing a fix.

Priority:
A question mark is visible, just not in the correct font. So marking as advanced.

3.3 Font styles, weight, etc

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.

#41 OK

GitHub issue #41

Adlam has no issues for this topic.

3.4 Glyph shaping and positioning

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.

#41 OK

GitHub issue #41

Adlam has no issues for this topic.

3.5 Cursive text

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.

#15 Text stroke cuts joining glyphs apart

GitHub issue #15

This issue is likely to apply to all cursive script text.

When text stroke effects are applied to cursive text, they wrap around the joining part of the glyphs, and interrupt the cursive flow.

This example shows the typical result for Adlam.

Screenshot 2021-01-22 at 16 12 12

And a similar result for N'Ko.

Screenshot 2021-02-16 at 07 20 44

For more details, see this GitHub issue, which is being used to track this gap. Please add any discussion there, and not to this issue.

#14 Text opacity shows glyph overlap

GitHub issue #14

This issue is likely to apply to all cursive script text.

Text in 'cursive' writing systems is joined by overlapping glyphs with the appropriate joining forms. If those glyphs are made opaque, the joins should not become apparent. For example, N'Ko should look like this:

Screenshot 2022-02-01 at 15 02 18

The GAP
When opacity is applied to text, some browsers produce dark patches where the cursive glyphs overlap. Here is an example in the Adlam script.

Screenshot 2021-01-22 at 15 52 10

And here is an N'Ko example.

Screenshot 2021-02-16 at 09 01 14

Gecko and Blink browsers show the unwanted overlaps. WebKit works as expected for Arabic, Devanagari, Syriac & N'Ko, but not for Adlam (Fulah), Mongolian, or Hanifi Rohingya.

Tests
Interactive test, Applying opacity to cursive text doesn't produce dark patches where glyphs overlap

I18n test suite, Text opacity
Contains similar tests for Arabic and Mongolian text, with the same results, except that WebKit browsers don't display Mongolian as cursive text, so the test is moot in that case.

Action taken:
Issue, Add note for text opacity applied to cursive scripts Closed.

Browser bug reports:
Gecko • Blink • WebKit

Outcomes:
2020-07-27: css-color was updated to clarify that opacity should be applied to a whole element, not to individual letters, so that this shouldn't happen.

Priority:
Marking as advanced, since this is a decorative feature.

#12 Inline elements break cursive shaping

GitHub issue #12

This issue is applicable to text in all cursive scripts.

When elements surround part of a cursive run of text, and apply styling, the results often break the cursive joins. (See the results of trying to colour individual letters in the illustration below – as expected above, unsuccessful below.)

Screenshot 2021-01-22 at 14 39 11

Screenshot 2021-01-22 at 14 36 42

For more details, see this GitHub issue, which is being used to track this gap. Please add any discussion there, and not to this issue.

3.6 Baselines, line-height, etc

Does the browser support requirements for baseline alignment between mixed scripts and in general? See available information or check for currently needed data.

#41 OK

GitHub issue #41

Adlam has no issues for this topic.

3.7 Transforming characters

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.

#21 Case conversion for Adlam

GitHub issue #21

This issue is applicable to languages using the Adlam script (mainly Fula).

Adlam is a bicameral script, and browsers need to apply the uppercase and lowercase features of CSS to Adlam text.

Specs: CSS Text provides the text-transform property, with values that include uppercase and lowercase.

Tests & results: Interactive test, CSS text-transform:uppercase converts all Adlam characters to uppercase

Interactive test, CSS text-transform:lowercase converts all Adlam characters to lowercase

Gecko, Blink, and Webkit all convert the characters correctly.

3.8 Grapheme/word segmentation & selection

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.

3.9 Punctuation & other inline features

Are there specific problems related to punctuation or the interaction of the text with punctuation (for example separation of punctuation from previous text, but allowing no line break between)? Are there issues related to handling of abbreviation, ellipsis, or iteration? Are there problems related to bracketing information or demarcating things such as proper nouns, etc? See available information or check for currently needed data.

#41 OK

GitHub issue #41

Adlam has no issues for this topic.

3.10 Text decoration

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.

#41 OK

GitHub issue #41

Adlam has no issues for this topic.

3.11 Quotations

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.

#41 OK

GitHub issue #41

Adlam has no issues for this topic.

3.12 Inline notes & annotations

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.

#41 OK

GitHub issue #41

Adlam has no issues for this topic.

3.13 Data formats & numbers

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)? How about the management of personal names, addresses, etc. in web pages: are there issues? See available information or check for currently needed data.

#41 OK

GitHub issue #41

Adlam has no issues for this topic.

4. Lines and Paragraphs

4.1 Line breaking

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.

See also hyphenation below.

4.2 Hyphenation

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.

4.3 Text alignment & justification

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.

4.4 Letter spacing

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.

4.5 Lists, counters, etc.

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.

#20 Adlam counter-styles are not available

GitHub issue #20

Customisable counters are needed for many languages.

There is no way for users to create local counter styles that are not built in to the browser, and users also often want to tweak the counter style in some way (esp. the prefix/suffix).

For Adlam, this means that the decimal numeric list style that uses Adlam digits cannot be used for CSS-styled counters.

More:

Priority: Adlam digits are used for counters in documents, and so should be available via CSS. Therefore, this is marked as a basic issue.

FIXED !
This gap is now fixed. For more details, see this GitHub issue, which is being used to track this gap. Please add any discussion there, and not to this issue.

4.6 Styling initials

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.

5. Page & book layout

5.1 General page layout & progression

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? Other topics that belong here include any local requirements for things such as printer marks, tables of contents and indexes. See available information or check for currently needed data.

5.2 Footnotes, endnotes, etc.

Does your script have special requirements for 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.

5.3 Page headers, footers, etc.

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.

5.4 Forms & user interaction

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.

6. Other

6.1 Culture-specific features

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).

6.2 What else?

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?

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