fragment letters...

Programer (
Sat, 5 Aug 1995 06:29:23 -0400 (EDT)

I was wondering if there is any standard to the letters in the international
designation....I've seen A-J common then there are a few T's and such....

is there any standard to all of this? or is it dependant on the 
particular satellite/rocket combination....(multi-payload vs 1 payload 
etc etc)