It’s amazing how hard it is for people to believe that you used carbon paper to make copies in the pre-Xerox photocopier days.
Reminds me of the old mimeograph machines I used to do word searches on for fellow students in class. 
It’s not that it’s hard for me to believe. I remember playing around with my dad’s carbon paper and manual typewriter. However, I was under the impression that the abbreviation preceded carbon paper.