[css-counter-styles] `system: extends decimal; fallback: decimal; speak-as: decimal`

[SimonSapin]

The system, fallback, and decimal descriptors all use <counter-style-name> in their value grammar definition, linking to:

https://drafts.csswg.org/css-counter-styles/#typedef-counter-style-name

The general form of an @counter-style rule is:

@counter-style <counter-style-name> { <declaration-list> }

where <counter-style-name> is a <custom-ident>.
If a counter style’s name is an ASCII case-insensitive match for "decimal" or "none", the @counter-style rule is invalid.

It is unclear whether the exclusion of "decimal" and "none" is part of the definition of the <counter-style-name> type, and therefore also applies when this type is used in descriptors, or whether that only applies to @counter-style rules.

Being able to use "decimal" makes sense. In fact that’s even the initial value, in the case of fallback. Using none less so. Maybe a different behavior is desirable for these two keywords?

By the way, why is "none" excluded when for example "inside" isn’t?

[upsuper]

It is unclear whether the exclusion of "decimal" and "none" is part of the definition of the <counter-style-name> type, and therefore also applies when this type is used in descriptors, or whether that only applies to @counter-style rules.

I don't think the exclusion of them is part of the definition of the <counter-style-name> type, because the last sentence is about "a counter style's name", and then, "the @counter-style rule is invalid". There is nothing about <counter-style-name> here.

[tabatkins]

Yup, exactly - those are restrictions on @counter-style definitions, not on <counter-style-name>.

By the way, why is "none" excluded when for example "inside" isn’t?

none is a valid value for list-style-type. inside is a different property entirely; I opted not to try to include the full set of list-style sub-property values.

[SimonSapin]

Just to clarify: system: extends none; fallback: none; speak-as: none is valid. (Though useless since there can’t be a counter style with that name.)