[scribus] Monochromatic Light: Is it in "the grayscale"?

[Barry McKenna]

So far I have no clues about how to import and/or apply a 
_gray/greyscale color profile to work with PDF/X-3.

But, in mylimited understanding, I've begun to work with a four-color 
text color set(including "Registration Black"), using "Monochromatic 
Light" (hopefully) as a gray.

It looks a bit blue, but then some grays do.

Am I cruzin' for a bruzin' here, or will my black text and 
"Monochromatic Light" (with grid-typegroup of marks changed to white) 
meet my publisher's "any grayscale profile requirements, as long as its 
PDF/X-3"?

Or, do I need to start learning that I'm not learning what I need to learn?

Barry