What does .C stand for?

What does .C mean?

C	Club Community » Sports
C	Clueless Academic & Science » Psychology
C	Coach Community » Sports
C	Coast Guard (military aircraft prefix) Miscellaneous » Aircraft
C	Cockroach Community » Housing
C	Cod Academic & Science » Ocean Science
C	Code Computing » Assembly
C	Coefficient Academic & Science » Mathematics
C	Coefficient Governmental » NASA
C	cold and clammy Medical » British Medicine
C	Collaboration Business » General
C	Collect Computing » Telecom
C	Collector (transistor) Academic & Science » Electronics
C	Color Community » Sports
C	Color Miscellaneous » Colors
C	Color Business » Products
C	Colorado Regional » States
C	Colored Miscellaneous » Colors
C	Colt Medical » Veterinary
C	Colt pistol Governmental » Military
C	Columbus Regional » States
C	Combat Governmental » Military
C	Combination Business » Products
C	Comedy Community » Media
C	Comfort Business » General