what is Uniform Chromaticity ?

Everywhere I read about uniform chromaticity spaces,but i can't find what uniform chromaticity is...Can anyone pls tell me what Uniform Chromaticity is?

[John D'Errico]

It is not a question about MATLAB, that is what it is. Ask it on a site about color science.

[Nicoleta]

Oh yes it is, because I need to decide whether to make conversion from RGB color space to a uniform chromaticity color space. I thought you already understand the purpose of the question because I know that this is a site about matlab,obviously.