Extension for material properties?

[Orion Pobursky]

(Since the topic has come up once more…)

Question:
Would it make sense to use the existing MATERIAL tag, but:

1. detach it from the !COLOUR meta into its own !MATERIAL meta, and
   
2. use it to define additional material categories within ldconfig, separate from colors so that each individual combination needn't be defined explicitly?
   

The problem is that they are very much intertwined. Yellow rubber is not the same yellow as yellow plastic. I'm not convinced there is a good solution to this.

Surface finish, on the other hand, could be specified with some sort of material tag.