Complex sentence: The colors in the Color Table are specified in the 4-byte per entry 8.8.8.0.8 format (in RGBAX notation) with an exception of the OS/2 BITMAPCOREHEADER's Color Table which uses the 3-byte per entry 8.8.8.0.0 format.
Split into simpler sentences: The colors in the Color Table are usually specified in the 4-byte per entry 8.8.8.0.8 format (in RGBAX notation). The Color Table used with the OS/2 BITMAPCOREHEADER uses the 3-byte per entry 8.8.8.0.0 format.