The definition of the internal DirectX D3DLVERTEX object is as follows:

struct D3DLVERTEX {
union {
D3DVALUE x;
D3DVALUE dvX;
};
union {
D3DVALUE y;
D3DVALUE dvY;
};
union {
D3DVALUE z;
D3DVALUE dvZ;
};
DWORD dwReserved;
union {
D3DCOLOR color;
D3DCOLOR dcColor;
};
union {
D3DCOLOR specular;
D3DCOLOR dcSpecular;
};
union {
D3DVALUE tu;
D3DVALUE dvTU;
};
union {
D3DVALUE tv;
D3DVALUE dvTV;
};
};