Header Files for DirectX 9.0 Drivers
A DirectX 9.0 display driver's source code must include the d3d9.h header file. The header files d3d9caps.h and d3d9types.h are included in d3d9.h.
To support DirectX 8.1 and earlier versions of the DirectX runtime, the driver's source code must include both old and new DirectX headers, for example d3d.h, d3d8.h, and d3d9.h.
To avoid problems when building a DirectX 9.0 version driver, define DIRECT3D_VERSION as 0x0900 in the driver's source code before including any header files. Doing so prevents the possibility of DirectX 9.0 features being missed as described in the DIRECT3D_VERSION topic. To ensure that the build process retrieves all the necessary symbols in header files, include d3d9.h and d3d8.h before winddi.h or d3dnthal.h.