[csswg-drafts] [css-values] Stacked modifiers in definitions (#6085)

dontcallmedom has just created a new issue for https://github.com/w3c/csswg-drafts:

== [css-values] Stacked modifiers in definitions ==
In https://github.com/w3c/svgwg/issues/642#issuecomment-474097525 @tabatkins indicates that the `+#`   stacked combinator is a valid way to declare the syntax of values that can be space- or comma-separated.

Reading [the Component Value Multipliers section](https://drafts.csswg.org/css-values/#component-multipliers), it's not all that clear that this is valid, or which modifiers can be stacked.

In particular, the various rules are expected to apply to types, keywords or bracketed groups - it's not clear whether a modifier applied to these still constitute a type, a keyword or a bracketed group.

There are already rules that says that the  ̀{A,B}` modifier can be stacked on top of `#`, which kind of implies stacking is the exception not the rule.

As we're looking in [reffy & webref to release the CSS syntax definitions as package](https://github.com/w3c/webref/pull/115#discussion_r587668547), we're trying to ensure the [csstree parser](https://github.com/csstree/csstree/blob/master/docs/definition-syntax.md) we're targeting as reference parser for these fragments can accommodate all the known valid CSS definitions, and so it would be useful to understand if indeed which of the stacked modifiers are indeed valid.

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/6085 using your GitHub account


-- 
Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config

Received on Monday, 8 March 2021 16:28:58 UTC