vertex color suggestion - another set - COLOR_0_s, COLOR_1_s, etc

I wanted to suggest another set of slots for vertex colors to include a subdivided set of vertices/colors.
The general idea is that vertex painting is very very nice for creating masks to use in pbr workflow, for roughness, specular, glossiness, etc, or to tamper a normal map in certain areas.
Of course, coming with benefit of no pixels in your masks due to interpolated nature.
But, often not used due to limitation of not having enough vertices to work with (mobile game optimized, for instance), thus subd for vertex colors would be great.
There would obviously need to be some mapping stored as well, from unsubd to subd.
Less overall data sent to gpu.
Not sure all the integration points.
Obviously would need to be built into DCC programs as well to be useful.
And Subd might not be the right idea here, but in general, some manner of getting textureless interpolated point color data to be used as a mask in shaders, with whatever mapping/intergration necessary, so we can paint masks with finer grained detail without resorting to textures.
I guess for display, there's no way getting around simply adding in additional shader code to use it, but that's expected really. If the data is there in some form as part of the mesh data, we can use.

The issue names no files or tests; begin by examining the glTF mesh vertex-color data, shader usage, and DCC-program integration points. Clarify the representation, mapping between original and subdivided vertices, and display behavior before defining what a complete implementation would require.

Written by the indexing model from the issue text.