|Microsoft DirectX 9.0|
The vertex declaration programs the vertex data direct memory access (DMA) and programs the tessellator engine of the graphics pipeline. It expresses the data layout and the tessellator operations concisely. To address the complexity and extensibility of declarations, a new format for expressing vertex streams has been introduced.
Vertex declarations are no longer expressed as streams of DWORDs; they are expressed as a an array of D3DVERTEXELEMENT9 structures. Each element of the array describes one vertex element.