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This document describes and prioritises gaps for the support of the N’Ko 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, such as HTML and CSS and those relating to digital publications. It also checks whether the features have been implemented in browsers and ereaders.
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 the N’Ko 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. It is linked to from the language matrix that tracks Web support for many languages.
The editor's draft of this document is being developed in the GitHub repository African Language Enablement (afrlreq), with contributors from the W3C Internationalization Interest Group. It is published by the Internationalization Working Group. The end target for this document is a Working Group Note.
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 03 November 2023 W3C Process Document.
The original version of this document was created by Richard Ishida.
Other contributors can be found in the GitHub contributors list.
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 that people encounter when trying to use languages written in the N’Ko 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.
A summary of this report and others can be found as part of the Language Matrix.
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 feature 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.
In what direction does text flow along a line and across a page? (See the Bidirectional text section if the basic direction is right-to-left.) If the script uses vertically oriented text, what are the requirements? 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?
Languages: nqo ff 2
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.
If the general inline direction is right-to-left, are there any issues when handling that? Where the inline direction of text is mixed, is this 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?
Languages: nqo ff 1
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.
Languages: nqo ff 3
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.
Languages: nqo ff 3
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 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.
This is an issue related to Unicode support, rather than W3C specs.
html mentions that text content may contain these characters.
i18n test suite, Isolating formatting characters
Webkit (2014)
WebKit now supports the required behaviour for these formatting characters. This means that they can be used interoperably on all major web browsers.These characters control fundamental behaviours for support of RTL scripts so priority is set as Basic.
Languages: nqo ff 1
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.
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?
Languages: nqo 1
This issue is applicable to N'Ko.
Letters in N'Ko text are normally joined (ie. 'cursive'), but instances can also be readily found of unjoined text, particularly in headings. Here is an example.
Note also that the heading text is bold. The text shown was achieved using legacy fonts that are not Unicode compatible.
For more information, see the language enablement requirements here and here.
Discussion thread: Non-joined fonts in N'Ko
There are only three Unicode compliant fonts in use, Noto Sans N'ko, Ebrima, and Kigelia, and none of them provide for unjoined text.Bold font faces are available for Ebrima and Kigelia, but not for Noto.
It is possible to use CSS to make a font show unjoined letters, if the OpenType features are available. Simply add something like this to your style sheet.
.unjoined { font-feature-settings: "init" 0, "medi" 0, "fina" 0, "isol" 1; }
But that's a little complicated for most people, and doesn't help those using Word, etc.
Bold, unjoined headings are a regular feature of N'Ko text, so it is problematic not to be able to produce them with the Noto font, and may even delay the migration of some users to Unicode.Interactive test, Exploratory test: N’Ko headings can be rendered unjoined and bolded.This does not need to be fixed in W3C specs or in browsers. Font developers need to provide appropriate fonts.Noto Unjoined and Unjoined Bold fonts are now available.
Languages: nqo ff 2
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.
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:
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:
Gecko is implementing a fix.
A question mark is visible, just not in the correct font. So marking as advanced.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?
Languages: nqo 3
This issue is applicable to N’Ko.
The World Organization for the Development of N'Ko prefers that all tone marks should appear at the same height above the baseline, rather than changing height according to the height of the base character to which they are attached. This image shows the preferred behaviour.
More:
The Noto Sans NKo font varies the height of the tone mark according to what it rests on. (The other major N'Ko Unicode fonts, Ebrima, Conakry, and Kigelia place tones at the same height.)More:
Character app test. Install the latest Noto Sans Nko font. Open the page and select Noto Sans NKo from the 'Current font' pulldown. Test passes if both tone marks are at the same height.Issue, Noto The latest release of the Noto N'Ko fonts now set above marks at a constant height. This means that all major N'Ko fonts now behave as expected.
Although this is the preference, the text is still readable, so this is marked as Advanced.
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?
Languages: nqo 1
This issue is applicable to Arabic/Persian, Hebrew, & N'Ko.
Typography for N’Ko is still at an early stage of development, but when JamraPatel reached out to communities to see if an Italic typeface would be beneficial, they expressed a desire to have one. Over the past few years, the need to be able to set more complex copy has increased as well. Since neither script had any precedent for a drawn italic typeface, JamraPatel asked the community how they would like to see it drawn. The preference was for N'ko to have a leftward lean. To JamraPatel's knowledge, their typeface has the first drawn italicized N'ko.
The following is a photo of an Arabic newspaper letterhead. See the oblique text in the middle line.
More:
Marking this as basic priority, given that incorrect synthesis is likely to occur often.
If a font is applied to create italicised or oblique text, there should be no problem here. But such font styles are sometimes achieved using font-synthesis, in which case the correct lean needs to be applied.
CSS provides for 'negative oblique' values of the font-style property, which can be used to achieve this. Set font-style to the desired value, such as -14deg and set font-synthesis-style to auto. Gecko supports that value, but Blink and WebKit do not.
However, there is a problem with the CSS approach because it suggests that if an italic font face is available for the font in use, then the font should be used rather than applying the oblique synthesis. (And this is what browsers appear to do.) In most cases, currently, this will result in right-leaning, italic glyphs (which may also have different shapes to oblique glyphs) rather than the specified left-leaning synthesized oblique or fallback to an oblique font face.
The following diagram shows the result of the second interactive test below, where no font-family
property is specified, and font-style:oblique -14deg
is applied to all lines. There is only one N'Ko font on the system and the system has no associated italic font file. The font set in browser preferences for Arabic text is also unaccompanied on the system by an italic font file. The Hebrew and Ukrainian texts are both represented by fonts for which an italic font file is also present on the system. The directive to apply -14 degree oblique to the latter two is overridden, and the text leans the wrong way. (And the letterforms for the cyrillic text are very different from those that would be produced by synthesising the oblique on the regular font.)
interactive test: It is possible to make synthetic oblique slant letterforms to the left.
interactive test: It is possible to slant glyphs to the left when the system has an italic font face.
CSS issue: (css-fonts) It should be possible to slant glyphs to the left for italics/oblique #8914Browser bug reports: WebKit • Blink
tbd
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?
Languages: nqo ff 2
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.
And a similar result for N'Ko.
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.
Languages: nqo ff 2
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:
When opacity is applied to text, some browsers produce dark patches where the cursive glyphs overlap. Here is an example in the Adlam script.
And here is an N'Ko example.
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.
Interactive test, Applying opacity to cursive text doesn't produce dark patches where glyphs overlapI18n 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.
Browser bug reports:
Gecko • Blink • WebKit
Languages: nqo ff 2
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.)
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.
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?
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?
Languages: nqo 3
This issue is applicable to N'Ko.
Certain constructs in N'Ko text mean 'each and every ....', and they appear with dash on the baseline with spaces either side. For example:
This is also used in other locations where we might use a dash in Latin text.
The question is what is the appropriate character for the te-kerende and other similar looking uses.
More:
This approach works in all browsers.
See an example page 3, col 2 (from the right), below the picture.
The Unicode Standard doesn't provide any advice on this topic. The original proposal included a request for a te-kerende character, but it was not adopted.
The question was raised at a Unicode Script Ad Hoc meeting.The Unicode Script Ad Hoc committee considered the matter and agreed that the te-kerende should be represented using<space><lajanyalan><space>
. This is already a de facto standard
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.)
Languages: nqo 3
This issue is applicable to N'Ko.
Certain constructs in N'Ko text mean 'each and every ....', and they appear with dash on the baseline with spaces either side. For example:
This is also used in other locations where we might use a dash in Latin text.
The question is what is the appropriate character for the te-kerende and other similar looking uses.
More:
This approach works in all browsers.
See an example page 3, col 2 (from the right), below the picture.
The Unicode Standard doesn't provide any advice on this topic. The original proposal included a request for a te-kerende character, but it was not adopted.
The question was raised at a Unicode Script Ad Hoc meeting.The Unicode Script Ad Hoc committee considered the matter and agreed that the te-kerende should be represented using<space><lajanyalan><space>
. This is already a de facto standard
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?
Are there any issues when dealing with quotations marks, especially when nested? Should block quotes be indented or handled specially?
How are emphasis and highlighting achieved? If lines or marks are drawn alongside, over or through the text, do they need to be a special distance from the text itself? Is it important to skip characters when underlining, etc? How do things change for vertically set text?
What characters or other methods are used to indicate abbreviation, ellipsis & repetition?
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.)
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?
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?
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?
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?
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.)
Does the browser support requirements for baseline alignment between mixed scripts and in general?
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?
Languages: nqo 3
This issue is applicable to languages using N'Ko and Adlam orthographies.
It must be possible for authors using the N'Ko orthography to create list and other counters using native digits.
This requires browser support for customised counter styles, since no browser supports N'Ko or Adlam counters natively.
More:
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.
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?
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.
Does the script have special requirements for character grids or tables?
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.)
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.
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?