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Re: [css-values] custom-idents and excluded keywords

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Thu, 17 Mar 2016 17:58:11 -0700
Message-ID: <CAAWBYDB0++7axZz3FU4ZwhiaQ4J6gEand8WOg5ZExtDVZjH+zA@mail.gmail.com>
To: Manuel Rego Casasnovas <rego@igalia.com>
Cc: www-style list <www-style@w3.org>
On Thu, Mar 17, 2016 at 1:51 AM, Manuel Rego Casasnovas <rego@igalia.com> wrote:
> in the CSS Values spec [1] we could find the following sentence:
> "This generic data type is denoted by <custom-ident>, and represents
>  any valid CSS identifier that would not be misinterpreted as a
>  pre-defined keyword in that property’s value definition."
> But a few lines later it says:
> "Specifications using <custom-ident> must specify clearly what other
>  keywords are excluded from <custom-ident>, if any—for example by
>  saying that any pre-defined keywords in that property’s value
>  definition are excluded."
> For example in the case of the CSS Grid Layout spec, it's not specified
> which keywords are excluded in the different properties that use
> <custom-ident> (for example the track sizing properties [2]).
> However, in a previous thread [3] Tab said that "minmax", "auto" and
> "subgrid" were not valid <custom-ident>.
> The question is if the CSS Grid Layout spec needs to be updated to
> specify the excluded keywords. Or the 2nd sentence above from the CSS
> Values spec needs to be removed/reworded.

Grid needs to be updated.  Previously, Values tried to *automatically*
define that keywords appearing the grammar at the same level were
excluded from <custom-ident>, but that ended up not actually working
in a reasonable way; it implied that different keywords could be
excluded between a longhand and a shorthand, for example.

That section of Grid was just written against the old text, and needs
to be updated to explicitly exclude the handful of keywords that can
appear near it.

Received on Friday, 18 March 2016 00:58:58 UTC

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