FVF (Flexible Vertex Format)
The driver's D3dDrawPrimitives2 callback receives vertex data in a flexible vertex format (FVF). Because the vertex format is flexible, there is no comprehensive data structure defined for this data. Drivers must implement full FVF functionality.
There is an FVF update for Microsoft DirectX 7.0 that includes 1D, 3D, and 4D textures in addition to the usual 2D textures. For more information about this update, see FVF Update. See the Perm3 sample driver and DirectX SDK documentation for more information about these topics.