The DDCOLORKEY structure describes a source color key, destination color key, or color space. A color key is specified if the low and high range values are the same. This structure is used with the IDirectDrawSurface4::GetColorKey and IDirectDrawSurface4::SetColorKey methods.
typedef struct _DDCOLORKEY{ 
    DWORD dwColorSpaceLowValue; 
    DWORD dwColorSpaceHighValue; 
} DDCOLORKEY,FAR* LPDDCOLORKEY; 
   Windows NT/2000: Requires Windows NT 4.0 SP3 or later.
  Windows 95/98: Requires Windows 95 or later. Available as a redistributable for Windows 95.
  Header: Declared in ddraw.h.