Ahh, those fun-loving guys at Kodak. They're the same people that brought us PhotoYcc, which was based on an RGB color space with physically-realizable primaries, but allowed negative amounts of them. Try that on your display!
Couple points. First, last time I looked, Lab which has a strange following also had negative numbers.
Have you ever seen what PhotoYCC in say Photoshop looks like (without the proper transforms)? Acid trip.
PhotoYCC was in a large way, the predecessor of the raw data so many of us today cherish. It was way ahead of it's time.
I'll let other's argue if "PhotoYcc, which was based on an RGB color space
" is valid.
We're talking numbers here which have no useful definition without a scale. That scale tells us the gamut among other things. The numbers can be CMYK, Lab or RGB and all could be out of display gamut. Life's a bitch. If your only interest is the output to a display, that's the only gamut you need to be concerned with. I'd shutter to think that in 10 years, the gamut of output devices the masses are using isn't wider than today. This is a moving target. We've seen this in relatively few years with both inkjet and traditional 4 color CMYK output.
WYS isn't always WYG but we strive to get as close as we can with the limitations of technology and a CMS and it's somewhat archaic basis and architecture.
If you want to dumb down the gamut of your output to match your display, that's pretty darn easy to do.