It is a 'fence mask' used in Spearhead, for example to determine surface properties for mixed textures like windows (part of the texture is wood, the other part is glass). I don't know how to make a fcm file or how to use it.
i got fcm files for some of my custom textures, and i did nothing for it. it seems to me as if the mohradiant/compiler/engine (???) makes it itself.
Anyway, i'd suggest: once u have one, put it into the pk3 together with the texture and forget about it if there isn't one.
