BUR #4749 has been rejected.
mass update greyscale spot_color -> spot_color -greyscale
mass update greyscale partially_colored -> partially_colored -greyscale
mass update greyscale flat_color -> flat_color -greyscale
By definition, greyscale images contain no color. Images with portions colored should be covered by spot_color, partially_colored, and/or the heresy we refer to as monochrome.