[css-fonts-3] Change @font-face and @font-feature-values syntax definitions to use CSS syntax and link to those definitions

[SebastianZ]

The current definition of the <family-name> type is:

The name of a font family of choice such as Helvetica or Verdana in the previous example.

And the <feature-index> and <feature-value-name> types are currently defined like this:

… the @font-feature-values rule is used to define values for a specific font family or set of families that associate a font-specific numeric <feature-index> with a custom <feature-value-name>, which is then used in this property to select specific alternates

This is somewhat vague, as there are no references to the related syntax definitions.

The definitions should be changed to use the syntax from the CSS Syntax Module.

I.e. they may look like this:

@font-face = @font-face { <declaration-list> }

where <declaration-list> can only contain the @font-face descriptors.

and

@font-feature-values = @font-feature-values <family-name># { <rule-list> }

<family-name> = <string> | <custom-ident>+

<feature-value-block> = <feature-type> { <declaration-list> }

<feature-type> = @stylistic | @historical-forms | @styleset | @character-variant | @swash | @ornaments | @annotation

<feature-value> = <integer>+

where <rule-list> can only contain <feature-value-block> rules, <feature-type> takes all font specific property names of font-variant-alternates prefixed with '@', <declaration-list> can only contain feature value definition properties holding <feature-value> values and the <integer> values in <feature-value> denote the feature indices.

The references to these syntax definitions should then link to them.

Sebastian

[tabatkins]

Updated @font-face and @font-palette-values.

@font-feature-values hasn't been moved to Fonts 4 yet, and I'm not about to go screw around with Fonts 3.

[svgeesus]

Yes, I need to port this over to Fonts 4, at which time it will use the CSS Syntax definitions.

We also resolved to remove @font-feature-values from Fonts 3 due to lack of two implementations, so that will deal with the obsolete syntax aspect for that part at least.

[svgeesus]

The relevant section now removed from Fonts 3. I'm editing the text now in Fonts 4 to use the syntax suggested in the initial post.