The Windows API represents a colour in terms of the intensity (in the range 0 to 255) of its red, green and blue components. Each component is thus an 8-bit value and the three components are packed into a 32-bit integer with the least significant 8 bits being red, the next 8 bits green and then blue. The most significant 8 bits are not used. The packing process is done for you by the function RGB@. For example RGB@(255,0,0) represents pure red.