Is it proper to use the abbreviation pc instead of cc? I have always used the abbreviation cc as a courtesy copy, however, I am told to use pc for photo copy at work. I have never seen this abbreviation used before outside of this office.
Courtesy Copy is a new "made-up" word. The first "c" has always stood for carbon. We have not made carpons for years. The letter "p" stands for photo and this term has been around for about 30 years.
I've never seen "p" either. Can I ask where you've seen that?
These days, they're not really photocopies either - you just print multiple copies of the original letter.
But as Nona says, it's whatever the convention is in your company.