Hey, looking at scanner sites around California it looks like the R.F.color box on the assignment card may refer to frequency alpha tags. Mine was showing copper and the frequency alpha tag showing on a scanner sites for the chp shows copper as an alpha tag for San Bernardino(860). According to this site the alpha tag might indicate what is displayed on a users radio or a channel designation by the agency.
http://www.radioreference.com/apps/db/?aid=995