what should monochrome option do exactly?

[Mojca M. <moj...@gm...>]

Hello,

I just remembered that implementation of monochrome option in context
terminal is slightly suboptimal (in standalone mode it lets TeX do
color conversion into gray scale as "rgb2gray").

I should probably fix that, but I'm not sure what exactly to do:
should I simply make all the colors black or should I use different
shades of gray, and in the second case - which colors exactly?

Thank you,
    Mojca