here's some more...
AA - Andrew A., the self-proclaimed original maker of screen-used helmets and armor.
ABS - Acrylonitrile-Butadiene-Styrene, a lightweight, rigid thermoplastic used to form white armor.
ACD - Armored Calvary Detachment
AFX - Armor FX, a supplier/producer/brand of stormtrooper armor.
AKA - Also known as (i.e. alias)
ANH - A New Hope, Star Wars Episode IV.
BBY - Before the Battle of Yavin.
BSN - Bikerscout.net, the official website of the scout trooper detachment.
C1 or CI - Star Wars Celebration I (1999).
C2 or CII - Star Wars Celebration II (2002).
C3 or CIII - Star Wars Celebration III (2005).
C4 or CIV Star Wars Celebration IV (2007).
CO - Commanding Officer.
CTN = Clonetroopers.net, the official website of the clonetroopers detachment.
D*C - Dragon Con, a large sci-fi convention held annually in Atlanta, Georgia (USA).
DL - Detachment Leader, elected head of a detachment.
DOA - Dead on arrival, often used to indicate something was broken when you received it.
ECG - Empire City Garrison
ESB - Empire Strikes Back, Star Wars Episode V.
EU - Expanded Universe, a term often applied to anything Star Wars that was not seen in the films themselves.
FIDM - Fashion Institute of Design Merchandising
FRS - Family Radio Service, a small and relatively inexpensive two-way radio system.
FISD- First Imperial Stormtrooper Detachment-The official website of the 501st stormtrooper detachment.
FX - Generally refers to Armor FX, a supplier/producer/brand of stormtrooper armor.
GF - Gerardo F., a one-time maker of screen accurate stormtrooper armor.
GL - George Lucas.
GT - Galaxy Trading
KOTOR - Knights of the Old Republic
KS - Kropserkel
LFL - Lucasfilm Limited
LOL - Laugh out loud.
MG - Mountain Garrison.
MOM - Magic of Myth, a traveling exhibit of Star Wars props that toured years ago.
MOTF - Matters of the Force, the Star Wars programming track at Dragon Con.
MWG - Midwest Garrison.
NEG - New England Garrison.
NER - Northeast Remnant garrison.
OL - Outpost Leader (equivalent of a CO).
OLG - Old Line Garrison.
OS - Outpost Second (equivalent of an XO).
PA - Polymer Armory
PVC - Polyvinyl chloride, a thermoplastic resin commonly used to create plastic pipes.
RA - Richie's Armor
RC - Republic Commando.
RL - Rebel Legion.
ROTJ - Return of the Jedi, Star Wars Episode VI.
RPF - Replica Props Forum, a non-501st forum for prop replication information sharing.
RS - Rebelscum.com, a website for the Star Wars collector.
SF - Star Fortress
RT-MOD- a supplier/producer/brand of stormtrooper armor.
SC - Studio Creations
SDCC - San Diego Comic Con, a large sci-fi con held annually in San Diego, California (USA).
SDS - Shepperton Studios
SL - Squad Leader.
SWW - Disney/MGM Studios Star Wars Weekends events held every summer in Orlando, Florida (USA).
TAG - Terror Australis Garrison
TBA - To be announced.
TBD - To be determined.
TDH - The Dented Helmet, a non-501st forum for Fett and related costuming discussions.
TE -Trooper Expert, a supplier/producer/brand of stormtrooper armor.
TFN - theforce.net, the official website of the Fan Force.
TFT - Toys for Tots, a U.S. charity that collects toys for Christmas distribution.
TM - Trooper Master, a supplier/producer/brand of stormtrooper armor.
TOD - Tour of duty, a record of your event attendance and participation.
UKG - United Kingdom Garrison.
VoNC - Vote of No Confidence.
XO - Executive Officer.