   UVW
  I don't understand which way the w component goes. It says it is perpendilcular to u and v, but that could be two directions.I am working on my 3dsmax exporter and I have to transform verts and normals to DirectX coord system, so I googles and settled on multiplying by[1 0 0][0 0 1][0 1 0]Now I want to do UVWs, but don't know what transform to use.I think if it was just UV, I would use[1 1][0 0]I'd like to keep the W component though, because I might actually use it one day. I don't know which way W goes in max or in DirectX. Which way?   
  I don't remember what this means in MAX, though in D3D you'd normally use it for volume textures. IMO if you don't need it and have no idea how it works, you can just ignore it. If you ever do need it, you will know at that time what it means and should have no problem adding support for it.   