A	Aerie of the slave lords (or Advanced)
AC	ACcessory
ALQ	Al Qadim
B	Basic
BSOLO	Basic Solo
C	Competition
CA	City Adventure
CB	Conan the Barbarian
CGR	Character Guide Reference?
CM	CoMpanion
CN	CoNan (not for D&D)
D	Drow
DA	Dave Arneson
DDA	Dungeons & Dragons Adventure
DDREF	Dungeons & Dragons Reference
DL	DragonLance
DLA	DragonLance Adventure
DLC	DragonLance Classic
DLE	DragonLance Epic
DLQ	DragonLance Quest
DLR	DragonLance Reference
DLS	DragonLance Saga
DLT	DragonLance Tales
DMR	Dungeon Master's Reference
DMGR	Dungeon Masters Guide Reference
DQ	Dragon Quest
DSE	Dark Sun Epic? 
DSM	Dark Sun Mission? 
DSQ	Dark Sun Quest 
DSR	Dark Sun Reference 
DSS	Dark Sun Sourcebook 
EX	EXtension
FA	Forgotten Realms Adventure
FMA	Forgotten Realms Maztica Adventure 
FMQ	Forgotten Realms Maztica Quest 
FOR	Forgotten Realms 
FR	Forgotten Realms
FRA	Forgotten Realms Adventure
FRC	Forgotten Realms Companion (some say Computer)
FRE	Forgotten Realms Epic
FRM	Forgotten Realms Mission?
FROA	Forgotten Realms Oriental Adventures
FRQ	Forgotten Realms Quest 
FRS	Forgotten Realms Sourcebook?
G	Giants
GA	General Adventure? 
GDQ	Giants, Drow, Queen of the demonweb pits
GAZ	GAZetteer
GM	Game Master (not by TSR)
GR	General Reference
H	High level
HCM	Hebrew Companion Modules
HHQ	Head-to-Head Quest 
HR	Historical Reference 
HWA	Hollow World Adventure 
HWQ	Hollow World Quest 
HWR	Hollow World Reference 
I	Intermediate level
IQ	InQuest 
IM	IMmortals
L	Lendore isles (or Low level)
LC	Living City
LNA	Lankhmar / Newhon Adventures
LNR	Lankhmar / Newhon Reference 
M	Master
MC	Monstrous Compendium
MSOLO	Marker SOLO (note: M2SOLO is confusingly labeled M2)
MV	Magic Viewer
N	Novice
O	One on one
OA	Oriental Adventures
OP	Outer Planes
PC	Player Character
PHBR	Player's HandBook Reference
Q	Queen of the demonweb pits
R	Role playing game association
RA	Ravenloft Adventure
REF	REFerence (REFeree?)
RM	Ravenloft Mission? 
RPGA	Role Playing Game Association
RQ	Ravenloft Quest 
RR	Ravenloft Reference
RS	Red Sonja (also Ravenloft Sourcebook)
S	Special
SJA	SpellJammer Adventure
SJQ	SpellJammer Quest 
SJR	SpellJammer Reference
SJS	SpellJammer Sourcebook
SJ	SpellJammer
ST	Steam Train (Stoke on Trent?)
T	Temple of elemental evil (or Towers)
TM	Trail Map
U	Underwater
UK	United Kingdom
WG	World of Greyhawk
WGA	World of Greyhawk Adventure
WGM	World of Greyhawk Mission?
WGQ	World of Greyhawk Quest
WGR	World of Greyhawk Reference
WGS	World of Greyhawk Swords
X	eXpert
XL	eXpert Ljn (as in LJN figures) (or eXpert Licensed)
XS	eXpert Solo
XSOLO	eXpert SOLO