Windows 3.1 Device Drivers (ddag31qh.hlp) (Table of Contents; Topic list)
COLORREF
COLORREF Specifies a 32-bit RGB color value or a logical color index. For
RGB color values, the high-order byte is zero, and bytes 0, 1, and 2
represent the intensity levels of blue, green, and red, respectively. For
logical color indexes, the high-order byte is 0xFF, and the low-order
16-bits represents the index.