LAB, is another popular color space, which should be mentioned. I used to work on a research project to match dental porcelain colors to actual tooth colors, and I had to write a program to calculate color differences. The LAB system is perceptually equalized so that the color differences are quantifiable, but it is nearly impossible to think in the LAB system. On the other hand it's pretty easy to visualize the proper color once you know it's Hue, Value and Chroma, so products are generally sold by Munsell color, but the Munsell system is not perceptually equalized because the color difference between one hew and another is arbitrary, so I had to convert everything over to LAB before any calculations could be done.
My point here, is that there is lots of important information about Color Spaces which has nothing to do with RGB, or CMYK. In particular, I think the notion of regular and irregular color spaces ought to be included somehow. On the other hand I did this work a long time ago (when I was 16) so my memory is a little fuzzy, and I have no references immediately available on the subject. MRC