Quake (3) *.map format

Hi there!
I wonder if anybody knows the exact meanings of the values per hull-plane of a brush. First three triples seem to be three vertices on the plane, the string afterwards is probably the shader used for the surface. But what then? How do the texture coordinates get specified? Something like the textures origin is in the center of the poly, and an angle? It would be really great if anybody could help!