REGION

typedef struct {
    WORD       id;        // if LPREGION 0x8000 else LPRECT
    WORD       cbSize;    // sizeof(REGION)
    LPRECT     lprcClip;  // NULL or region walking opt
    DWORD      dwUniq;    // region uniqueness value
    RECT       rcBBox;    // bounding box of region
    DWORD      cScans;    // count of scans in region
    LPSCAN     lpScan;    // ptr to first scan in region
} REGION;

Defines the attributes, bounding box, and scan lines of a region.