Re: [csswg-drafts] [css-text-4] Should mention on variation selectors (especially for `text-spacing-trim`) (#13654)

As you have pointed out, "typographic character units" are nearly equivalent to grapheme clusters and "base character" is found in many place in CSS Text:

> <dl><dt>ideographs</dt>
> <dd>
> 
> Includes all [typographic character units](https://drafts.csswg.org/css-text-4/#typographic-character-unit) [\[CSS-TEXT-3\]](https://drafts.csswg.org/css-text-4/#biblio-css-text-3 "CSS Text Module Level 3") whose base character is listed below:
> 
>   - All characters in the range of U+3041 to U+30FF, except those that belong to Unicode Punctuation \[P\*] [general category](https://drafts.csswg.org/css-text-4/#unicode-general-category).
>   - CJK Strokes (U+31C0 to U+31EF).
>   - Katakana Phonetic Extensions (U+31F0 to U+31FF).
>   - All characters that have the Han [script property](https://drafts.csswg.org/css-text-4/#unicode-script).
> 
> </dd>
> <dt>non-ideographic letters</dt>
> <dd>
> 
> Includes all [typographic character units](https://drafts.csswg.org/css-text-4/#typographic-character-unit) that belong to Unicode Letters \[L\*] and Mark \[M\*] [general category](https://drafts.csswg.org/css-text-4/#unicode-general-category), except when any of the following conditions are met:
> 
>   - is defined as [ideograph](https://drafts.csswg.org/css-text-4/#ideographs).
> 
>   - is categorized as East Asian Fullwidth (F) by [\[UAX11\]](https://drafts.csswg.org/css-text-4/#biblio-uax11 "East Asian Width").
> 
>   - is upright in vertical text flow using the [text-orientation](https://drafts.csswg.org/css-writing-modes-4/#propdef-text-orientation) property or the [text-combine-upright](https://drafts.csswg.org/css-writing-modes-4/#propdef-text-combine-upright) property.
> 
> <dt>non-ideographic numerals</dt>
> <dd>
> 
> - Includes all [typographic character](https://drafts.csswg.org/css-text-4/#typographic-character-unit) units that belong to the Unicode Decimal Digit Number \[Nd] [general category](https://drafts.csswg.org/css-text-4/#unicode-general-category), except when any of the following conditions are met:
> 
>   - is categorized as East Asian Fullwidth (F) by [\[UAX11\]](https://drafts.csswg.org/css-text-4/#biblio-uax11 "East Asian Width").
>   - is upright in vertical text flow using the [text-orientation](https://drafts.csswg.org/css-writing-modes-4/#propdef-text-orientation) property or the [text-combine-upright](https://drafts.csswg.org/css-writing-modes-4/#propdef-text-combine-upright) property.
> 
> </dd>
> </dl>

However, no "base character" or "typographic character units" is used for the definitions of  "fullwidth \<category> punctuation":

> <dl>
> <dt>fullwidth opening punctuation</dt>
> <dd>
> 
> Includes any opening punctuation character (Unicode category `Ps`) that belongs to the CJK Symbols and Punctuation block (U+3000–U+303F) or is categorized as East Asian Fullwidth (F) by [\[UAX11\]](https://drafts.csswg.org/css-text-4/#biblio-uax11 "East Asian Width"). Also includes LEFT SINGLE QUOTATION MARK (U+2018) and LEFT DOUBLE QUOTATION MARK (U+201C). When trimmed, the left (for horizontal text) or top (for vertical text) half is kerned.
> 
> </dd>
> <dt>fullwidth closing punctuation</dt>
> <dd>
> 
> Includes any closing punctuation character (Unicode category `Pe`) that belongs to the CJK Symbols and Punctuation block (U+3000–U+303F) or is categorized as East Asian Fullwidth (F) by [\[UAX11\]](https://drafts.csswg.org/css-text-4/#biblio-uax11 "East Asian Width"). Also includes RIGHT SINGLE QUOTATION MARK (U+2019) and RIGHT DOUBLE QUOTATION MARK (U+201D). May also include [fullwidth colon punctuation](https://drafts.csswg.org/css-text-4/#fullwidth-colon-punctuation) and/or [fullwidth dot punctuation](https://drafts.csswg.org/css-text-4/#fullwidth-dot-punctuation) ([see below](https://drafts.csswg.org/css-text-4/#fullwidth-ambiguous)). When trimmed, the right (for horizontal text) or bottom (for vertical text) half is kerned.
> 
> </dd>
> <dt>fullwidth middle dot punctuation</dt>
> <dd>
> 
> Includes MIDDLE DOT (U+00B7), HYPHENATION POINT (U+2027), and KATAKANA MIDDLE DOT (U+30FB). May also include [fullwidth colon punctuation](https://drafts.csswg.org/css-text-4/#fullwidth-colon-punctuation) and/or [fullwidth dot punctuation](https://drafts.csswg.org/css-text-4/#fullwidth-dot-punctuation) ([see below](https://drafts.csswg.org/css-text-4/#fullwidth-ambiguous)).
> 
> </dd>
> <dt>fullwidth colon punctuation</dt>
> <dd>
> 
> Includes FULLWIDTH COLON (U+FF1A) and FULLWIDTH SEMICOLON (U+FF1B).
> 
> </dd>
> <dt>fullwidth dot punctuation</dt>
> <dd>
> 
> Includes IDEOGRAPHIC COMMA (U+3001), IDEOGRAPHIC FULL STOP (U+3002), FULLWIDTH COMMA (U+FF0C), FULLWIDTH FULL STOP (U+FF0E).
> 
> </dd>
> </dl>

I don't think these definitions don't assume the above variation sequences. In the first place, "character" there is ambiguous.

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Received on Saturday, 21 March 2026 10:50:31 UTC