Clarified and included CJK requirements in large text definition and updated rules affected by this change

[giacomo-petri]

Since the WCAG is not unambiguously defining what "equivalent size for Chinese, Japanese and Korean (CJK) fonts" means, I've added the definition of large text for CJK languages, based on the Japanese translation of WCAG 2.1 with the assumption that it applies also to the other CJK languages.

Edits:

• updated the large text definition;
• updated ACT contrast minimum examples to reflect updates;
• updated ACT contrast enhanced examples to reflect updates.

Closes #2068

Need for Call for Review:
This will require a 2 weeks Call for Review

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[WilcoFiers]

I rewrote a few things, including updating the links as I found this a little difficult to read with all the URLs in them:

**Exception**: If the text nodes contain Unicode characters in the 4E00–9FFF range:

- at least 22 [points][], or
- at least 18 [points][] and a [computed][] [font weight][] CSS property of 700 or higher.

**Notes:**  
The WCAG definition of [large scale text](https://www.w3.org/TR/WCAG21/#dfn-large-scale) includes an exception for CJK (Chinese, Japanese, and Korean) text. The Unicode range 4E00–9FFF includes these characters. The "equivalent size" numbers are not included in WCAG, and come from the [Official Japanese Translation of WCAG 2.1](https://waic.jp/translations/WCAG21/#dfn-large-scale).  This translation offers the following insight (translated from Japanese to English to allow everyone understanding the specs):  

> TRANSLATION NOTE  
> In the case of Japanese full-width characters, 22 point or 18 point bold type is considered to be the "equivalent" size, based on the First Report of the Enlarged Textbook Promotion Council, "Chapter 2 Standards for Enlarged Textbooks." is reasonable."
Assuming all CJK characters pose similar contrast challanges, this definition extends the Japanese requirement to the whole CJK characters set included in the [Unicode standard](https://unicode.org/charts/PDF/U4E00.pdf) within the range of 4E00–9FFF.

[computed]: https://www.w3.org/TR/css-cascade-3/#computed-value
[font-size]: https://www.w3.org/TR/css-fonts-3/#propdef-font-size
[points]: https://www.w3.org/TR/css-values/#pt
[font weight]: https://www.w3.org/TR/css-fonts-3/#font-weight-prop

[JediLin]

Taiwan has different requirements than Japan, I propose the following:

**Exception**:  
A text node containing Unicode characters in the 4E00–9FFF range ([CJK Unified Ideographs](https://unicode.org/charts/PDF/U4E00.pdf)) is <dfn id="large-scale-text:cjk">large scale text</dfn> if at least one of the following is true:

- the Japanese text node [computed][] [font-size][] is at least 22 [points][], or
- the Traditional Chinese text node [computed][] [font-size][] is at least 20 [points][], or
- the Japanese text node [computed][] [font-size][] is at least 18 [points][] and has a [computed][] [font weight][] of 700 or higher, or
- the Traditional Chinese text node [computed][] [font-size][] is at least 16 [points][] and has a [computed][] [font weight][] of 700 or higher.

**Notes:**  
The WCAG definition of [large scale text](https://www.w3.org/TR/WCAG21/#dfn-large-scale) includes an exception for CJK (Chinese, Japanese, and Korean) fonts. The Unicode range 4E00–9FFF includes these characters. The "equivalent size" numbers are not included in WCAG, and come from the [Taiwanese Readability Reference Guidelines](https://crpd.sfaa.gov.tw/BulletinCtrl?func=downloadFile&type=file&id=3749&code=F9FEF1F8F1FAF6FAFCFAFCFCFFFAF2F3) (PDF download) and the [Unofficial Japanese Translation of WCAG 2.1](https://waic.jp/translations/WCAG21/#dfn-large-scale). The Taiwanese Readability Reference Guidelines requires minimal font size 16 points for Traditional Chinese characters and 14 points for English characters to be fulfill the need of the people with disabilities, and the Unofficial Japanese translation offers the following insight (translated from Japanese to English to allow everyone understanding the specs):

[carlosapaduarte]

Some editorial suggestions for the definition

[carlosapaduarte]

We might want to indicate that that Unicode range describes the CJK Unified Ideographs

[giacomo-petri]

Added at the beginning of the Exception for a better understanding

[carlosapaduarte]

Suggested change

	For CJK (Chinese, Japanese and Korean) characters with a [computed](https://www.w3.org/TR/css-cascade-3/#computed-value) [font-size](https://www.w3.org/TR/css-fonts-3/#propdef-font-size) of:
	For CJK (Chinese, Japanese and Korean) characters within text nodes, a [computed](https://www.w3.org/TR/css-cascade-3/#computed-value) [font-size](https://www.w3.org/TR/css-fonts-3/#propdef-font-size) of:

[Jym77]

Well done.

I think we should vary the languages in the new examples and have some in Korean or Chinese (OK, Chinese will be the same character set…)

[Jym77]

Isn't that an unofficial translation?

[giacomo-petri]

Missed it while accepting Wilco suggestion. Good catch.
Updated

[Jym77]

Suggestion: I think we should rephrase the full definition (as it doesn't look like correct English now), in the line of:

A text node is large scale text if its [computed][] [font-size][] is:

• at least 18 [points[]; or
• at least 14 [points][] and its [computed][] [font+weight][] is at least 700.

Exception:
A text node containing CJK characters is large scale text if …

Maybe even start the definition with "depending whether the text node contains CJK characters, …" 🤔

Also, if the defined term instances (_large scale text_) are wrapped in a dfn element, we can reference them directly from the running text:

<dfn id="large-scale-text:cjk">large scale text</dfn>
This is [large scale text][#large-scale-text:cjk]

See, e.g. attribute value in image button name rule

Additionally (but not directly related to this PR, so may be taken separately):

• These lists do not match how we write condition lists now; should be "if at least one of the following is true: the [computed][] [font-size][] is at least 18 points; or…"
• Technically, text nodes do not have CSS properties, only their parent element has, so the language used here is a bit incorrect (although not really confusing…)
• Also, not need to say "[font weight][] CSS propert" when the name already links to CSS specs.

[giacomo-petri]

Suggestions applied rewriting the definition and starting with "A text node..."

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Additionally (but not directly related to this PR, so may be taken separately):

These lists do not match how we write condition lists now; should be "if at least one of the following is true: the [computed][] [font-size][] is at least 18 points; or…"

Happy to edit condition lists and include them in the current edits.

Technically, text nodes do not have CSS properties, only their parent element has, so the language used here is a bit incorrect (although not really confusing…)

You're absolutely right. This was the case in the previous iteration as well. I'm struggling to find a straightforward method to enhance its clarity without adding more complexity to the definition.

Also, not need to say "[font weight][] CSS propert" when the name already links to CSS specs.

updated.

requirements changed based on ACT meeting

[Jym77]

• I believe we also need to have the note about CJK (or part of it) directly in the rules, in the lines of:

  For CJK characters used in some languages and countries, a font size of 18-22pt should not be consider "large text". These may fail the SC while still passing the rule.

• We can keep some CJK examples, to show we've considered them.

rule updated

[giacomo-petri]

Call for review ends on April 16th April 23rd (2 weeks).

[Jym77]

Call for review has ended, merging.