In the printing world it's called Rich Black
Mainly when working with 4 color print jobs (CMYK). Just black just isn't dark enough, and every print house has their prefered Rich Black Formula. I've had to mess with this with geologic maps I've published, but I can't do it in AutoCad because it is only RGB color. So I have to bring the drawing into Illustrator and fix the black there (as well as all the other artifacts that come through.)