Writing Color Keyword
W parameter and switch alternative, default is 0 (black). N is a kilo color spec. Turns on <RtfColorOverride>, has little if any effect unless <RtfColorOverride> is on. When used as a parameter it sets the default writing color for all frames, when used in a frame it sets the writing color for just that frame.
DMDX by default uses the color scheme present in the RTF item file, part of the WYSIWYG thing. In order to specify text color in the same way that previous versions of Dmastr did DMDX must be told to stop doing this with the <RtfColorOverride> MDSP bit.