The definition of the internal DirectX D3DRECT object is as follows:

struct D3DRECT {
union {
LONG x1;
LONG lX1;
};
union {
LONG y1;
LONG lY1;
};
union {
LONG x2;
LONG lX2;
};
union {
LONG y2;
LONG lY2;
};
};