I stumpled upon a ambiguous color definition in my automatically generated documents:


I.e. the color is defined in CMYK mode as 100% magenta and in RGB as 0/0/0 black. In the PDF the color is shown as black, according to Acrobat's preflight defined as RGB 0/0/0; CMYK separation depends on the profile, e.g.:
Generic CMYK:        76/71/65/81
ISO Coated FOGRA27:  86/85/79/100
Euroscale Coated:    95/83/82/90
(I didn't expect the Euroscale Coated profiles to differ that much!)

If I say \setupcolors[rgb=no], I get CMYK 100/100/100/0.
This is not a good separation algorithm - GCR or UCR would be nice, but at least RGB 0/0/0 should render as CMYK 0/0/0/100. (Perhaps you could include something like littleCMS in LuaTeX and even deal with images?)

It doesn't change if I define in different order, like \definecolor[Custom][r=0,g=0,b=0,c=0,m=1,y=0,k=0,]
I get magenta only if I leave out the RGB values.

It seems that in ConTeXt the RGB definition always takes precedence? Is this intended?

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