[meta] CSS Value Definition Syntax issues

[tidoust]

Here is a list of issues found while trying to extract CSS value definitions from CSS specs. Most of them are editorial in essence, some may be due to misreading (or reading too much into) the Value Definition Syntax:

• [css-backgrounds] Use of   in Bikeshed source for "Applies to" and "Computed value" headers makes columns appear twice in property index (see [css-backgrounds] Remove non-breakable spaces (or use them consistently) csswg-drafts#2911)
• [css-rhythm] Missing quotes around property refs in block-step dfn (see [css-align] [css-flexbox] [css-overflow] [css-rhythm] [css-shapes] [css-ui] Missing quotes around property refs csswg-drafts#2912)
• [css-shapes] Missing quotes around property ref in polygon() dfn (see [css-align] [css-flexbox] [css-overflow] [css-rhythm] [css-shapes] [css-ui] Missing quotes around property refs csswg-drafts#2912)
• [css-shapes] Missing quotes around property ref in path() dfn (see [css-align] [css-flexbox] [css-overflow] [css-rhythm] [css-shapes] [css-ui] Missing quotes around property refs csswg-drafts#2912)
• [css-flexbox] Missing quotes around property refs in flex-flow dfn (see [css-align] [css-flexbox] [css-overflow] [css-rhythm] [css-shapes] [css-ui] Missing quotes around property refs csswg-drafts#2912)
• [css-ui] Missing quotes around property refs in outline dfn (see [css-align] [css-flexbox] [css-overflow] [css-rhythm] [css-shapes] [css-ui] Missing quotes around property refs csswg-drafts#2912)
• [css-align] Missing quotes around property refs in place-items dfn (see [css-align] [css-flexbox] [css-overflow] [css-rhythm] [css-shapes] [css-ui] Missing quotes around property refs csswg-drafts#2912)
• [css-overflow] Missing quotes around property ref in line-clamp dfn (see [css-align] [css-flexbox] [css-overflow] [css-rhythm] [css-shapes] [css-ui] Missing quotes around property refs csswg-drafts#2912)
• [fill-stroke] Missing quotes around property ref in fill dfn (see [fill-stroke] Missing quotes around property ref, and not a real "value" fxtf-drafts#300)
• [fill-stroke] The fill dfn is actual prose, not a string that follows the Value Definition Syntax. (see [fill-stroke] Missing quotes around property ref, and not a real "value" fxtf-drafts#300)
• [filter-effects] <url> should rather link to the real <url> dfn (see [filter-effects] Have <url> link to the dfn in CSS Values fxtf-drafts#301)
• [svg-markers] compound-selector should be <compound-selector> in the <child-selector> dfn (see Incorrect syntax for <child-selector> dfn svgwg#498)
• [css-grid] The <track-repeat> dfn references <positive-integer>, which is not defined in any CSS spec (see [css-values] Define value syntax that limits <integer>, <number>, <length>, etc. to ranges csswg-drafts#355)
• [css-fonts] Missing quotes around { and } in <feature-value-block> dfn (see [css-fonts] Missing quotes in <feature-value-block> dfn csswg-drafts#2915)
• [css-backgrounds] The border-color dfn value should probably be [<color>{1,4}]# instead of (<color>{1,4})# (see [css-backgrounds] Incorrect value dfn for border-color and background-clip csswg-drafts#2916)
• [css-backgrounds] In the border-color dfn, the "Value" header should link to https://drafts.csswg.org/css-values/#value-defs (see [css-backgrounds] Incorrect value dfn for border-color and background-clip csswg-drafts#2916)
• [css-backgrounds] New values for background-clip should use | to separate values as in other specs (see [css-backgrounds] Incorrect value dfn for border-color and background-clip csswg-drafts#2916)
• [css-grid] Not clear how to intepret the repeat dfn. Does [ | auto-fill ] mean an empty value is allowed? What does the + apply to? Shouldn't it be a # (without comma)? (see [css-grid] Not clear how to read the <name-repeat> dfn csswg-drafts#2917)
• [css-tables] The border-spacing dfn value has zero-width spaces around length, see (well, with an hex editor, otherwise you won't see much) the corresponding line in source file) which make the value invalid per the Value Definition Syntax. (see [css-tables] Zero-width spaces in border-spacing dfn csswg-drafts#2918)
• [css-gcpm] The term content-list should rather be content-level to match the prose, and should probably be <content-level> to match conventions used in other CSS specs (see [css-gcpm] "content-list" should rather be "<content-level>" csswg-drafts#2919)
• [compositing] No easy way to tell that the <blend-mode> dfn is a production rule. Other specs have a css class. (see [compositing] Consider tagging the <blend-mode> and <isolation-mode> production rules fxtf-drafts#302)
• [svg] No easy way to tell that the <dasharray> dfn is a production rule. Other specs have a css class. (see Consider tagging the <dasharray> production rule svgwg#499)
• [css-fonts] The value of the src descriptor should not be "see prose" but rather a string that follows the Value Definition Syntax. It was defined with such a string in Level 3. Is that no longer doable? (see [css-fonts] Unexpected "see prose" value for src descriptor csswg-drafts#2920)
• [css-values] Keyword values do not allow for some of the values used in specs. The syntax says that keyword values are identifiers and as such conform to the <ident-token> grammar, which does not allow values to start with a digit or an @. However, some values need that such as glyph-orientation-vertical, font-weight (although replaced by <number> in Level 4), or @stylistic (see [css-values] Automatic parsing of value definitions csswg-drafts#2921)
• [css-values] Definition equations are not defined in the Value Definition Syntax. In other words, the use of =, and the description of how to read the left-side seems to be missing. For non-terminals, most specs use <non-terminal-name> = <dfn> equations, but <> are sometimes omitted on the left-side as in the inset() dfn and content-list dfn, or there may be no = sign as in the fade() dfn. Also, some definitions use a final semi-colon as in CSS Display, CSS Box Alignment and CSS Counter Styles, but most don't. (see [css-values] Automatic parsing of value definitions csswg-drafts#2921)
• [css-syntax] Dagger characters are not allowed by the Value Definition Syntax in the <an+b> dfn (see [css-values] Automatic parsing of value definitions csswg-drafts#2921)
• [bikeshed] Curly quotes should not replace single quotes in dfn values, as done in flex dfn, since grammar does not allow for it. (see [css-values] Automatic parsing of value definitions csswg-drafts#2921)

[dontcallmedom]

I've updated the list of items to be checked off; I haven't deteremined which subset of w3c/csswg-drafts#2921 still needs to be done.

I noted that it was suggested we bring the "missing rules" list as a separate github issue - @tidoust, do you know if we ever did that? (the list might need an update too)

[tidoust]

I noted that it was suggested we bring the "missing rules" list as a separate github issue - @tidoust, do you know if we ever did that? (the list might need an update too)

No, I think that is still a TODO.