[css-fonts-4] The 'features' value of 'font-technology' needs a parameter to identify the specific feature/shaping technology #6372
Description
In the font-technology options for the supports clause of the src descriptor, the color(...) value takes an argument that identifies which specific color technology is used.
However, features does not currently have a similar argument; I think it should. There are at least three distinct font-feature technologies in current use that each may (or may not) be individually supported by a given user agent: OpenType layout (GSUB/GPOS tables), AAT (morx/kerx tables), and Graphite (Silf and related tables). Given that not all browsers support all of these, the bare keyword features is insufficient to determine whether a given resource should be used.
Therefore, I propose that features, like color(), should take a keyword argument specifying which font feature technology is present; possible values would be ot (or opentype?), aat, and graphite. This allows browsers to load only font resources they can properly use, and enables authors to provide alternative fonts if needed.