According to a recent edit in another article, "The Focal Encyclopedia Of Photography, Third Edition. Eds. L Strobel and R. Zakia, page 544)" claims that "PC" stands for "Pin Cylinder", not "Prontor-Compur".
It is my assumption that this is an attempt to coin kind of a backroym, since the original meaning of "PC" as "Prontor-Compur" (two makers of shutters) may not be widely known outside of Europe. Comments welcome. --Matthiaspaul (talk) 20:42, 14 August 2012 (UTC)