Comment 2 for bug 1620621

No objections to merging the bugs.

The reason for this and the former request is that CIE xyY is what's apparently used to define a 'color-region'(i.e tolerance) used in certain technical applications.

The relevant document I was looking at being -
http://mutcd.fhwa.dot.gov/texts/colorspecfr.pdf

The equivalent British Standard (12899-1) (which I can't link as it's not freeely online) specifies it's colours in a similar manner.

I appreciate that Inkscape isn't necessarily designed with technical applications in mind ( I'm not aware of any "free" CAD systems for drawing road signs though.), but where there is a technical standard, it seems reasonable to make use of it.

Some of the conversion formulae appear to be documented here :-
http://www.brucelindbloom.com/index.html?ColorCalculator.html
But the site claims it's own copyright.