The CMYK (Cyan, Magenta, Yellow and Key (black) ) color model is used by commercial printers. CMY and K are the four inks used in full color printing. The Key color is used to reinforce dark colors which would appear 'muddy' if printed using only C, M and Y. If the Key is set to 100%, the color will appear black irrespective of the settings of C, M and Y. CMYK colors are stored in 32-bit format. They are printed (and output in EPS) in CMYK format unless the document uses transparency or shadows when they are converted to RGB. You can preview the different CMYK plates within Xara LX by Simulating Printer Colors.