   Adjacency Data
  I have seen the word "adjacency" appear both in ID3DX10MESH, and in the D3D10_PRIMITIVE_TOPOLOGY, however in both places it is simply described as "adjacency data". Well, gee that tells me alot. I know what the word adjacent means, but what does this data look like, how is it used?   
  From memory it's adjacent faces. In the material buffer you can get an index for each face, and the adjacency buffer has three times this number of indices - for each face it lists the 3 adjacent faces to that triangle.The D3D9 docs have some information and as far as I'm aware it hasn't changed for D3D10.hthJack   