List of Convoy Identification Codes
Based on "The Allied Convoy System 1939-45"(see links) with additions.

There were more than 200 convoy routes in existence during the war of which 94 routes were under attack by U-boats.  Each convoy was known by two or more letters designating the route and a consecutive number added in chronological order.  Additionally, the letter 'F' was sometimes used to identify fast convoys (9 knots) and 'S' for slow ones (7 knots).   The convoys received the number when they left harbour.  Vessels that could make 13 knots or more could qualify for independent sailing but the losses amongst this group were three times higher than for those travelling in convoy.
 

 
 
A
AB         Two "one off" convoys of early date (one from August 1939!).
AB          Commenced in Sept 1942, Aden to Bombay
ABF        The Fast, i.e. troopship, successor to AB, Aden to Bombay.
AC          A 1941 series, Alexandria to Cyrenaica i.e. Tobruk.
AG          Alexandria to Greece, a 1941 series.
AH          Aruba to Halifax, a brief tanker series in 1942.
AH          Augusta to Heel of Italy, post Sept 1943.
AJ           Aden to Colombo. "J" probably refers to Jaffna.
AK          Aden to Kilindini, commenced in 1942.
AKD       Aden to Kilindini and Durban.
AM         Chittagong to Madras.
AN          Aegean Northward, i.e. Alexandria to Piraeus 1940  & 1941.
AN          Admiralty Islands to New Guinea. (troop convoys UK  to Egypt in mid 1940).
ARG       Boston to Argentina--USN convoys.
ARM      A local Mediterranean code, little used.
AS          Aegean Southward, i.e. Piraeus to Alexandria 1940 & 1941.
AS          America to Suez, convoys New York to Suez via Freetown in 1942.
AT          Alexandria to Tobruk commencing late 1941.
AT          USA to UK troopship series 1942-45.
ATM      Antwerp to Thames, a late 1944 & 1945 series.
AW        Aruba to Curacao (Willemstad) local tanker traffic.
BTOP
BA          Bombay to Aden, reversal of AB.
BAF        Bombay to Aden Fast, troopships, reverse of ABE.
BE           Belfast to Bristol Channel 1940 to 1943.
BE           Clyde to Bristol Channel 1945.
BC           Beira to Durban, probably coded as Beira-Cape.
BC           Bristol Channel to Biscay, outward & return carried same number.
ED           White Sea to Dikson Sept 1943 onward, new numbers each year.
BEC        The retitled EBC series--qv.
BF           Bahia, Brazil to Freetown, a US series from 1943.
BG           A Pacific series, Milne Bay to New Guinea.
BG           A Pacific series, Brisbane to Gladstone.
BHX       Bermuda to rendezvous with the same number HX convoy.
BK          A little used Bombay to Karachi series in 1943.
BK          White Sea to Kola Inlet Sept 1943 onward, new numbers each year.
"Blue"    The early Port Said to Gibraltar convoys of 1939.
BM         Bombay to Singapore to Jan 42 then Bombay-Colombo traffic.
BN          Bombay Northward, (Bombay to Suez, then Aden to Suez), 1940-41.
BN          A later, Pacific, series, New Britain to New Guinea.
BP           Bombay to Persian Gulf.
BRN        Bahia, Brazil, Recife Northward.
BS           Suez to Aden late 1940 and early 1941.
BS           A brief Canadian series Corner Brook to Sydney CB.
BS           French convoys Brest to Casablanca 1933-40.
BT           Bahia, Brazil to Trinidad commenced Jan 1943.
BT           Sydney NSW to USA troop convoys 1943-44.
BT           Brisbane to Townsville.
BTC        Bristol Channel to Thames 1944-45.
BV           A Pacific series, Brisbane to Townsville.
BW         Sydney CB to St John's NF commenced 1942.
BX          Boston to Halifax.
BZ           Proposed Bombay-Kilindini-Aden series, not used.
CTOP
C             Colombo to dispersal, 1942 series.
CA          Capetown southward to dispersal.
CB           Durban to Beira.
CD          Capetown to Durban.
CE           Channel Eastward i.e. St Helens Roads to Southend.
CF           Capetown to W. Africa and UK, a little used series.
CF           Colombo to Fremantle, occasional use only.
CG           Casablanca to Gibraltar.
CH          Chittagong to Calcutta.
CJ            Calcutta to Colombo.
CK          Havana (Cuba)     to Key    West.
CK          Charleston  SC to UK, rarely used 1944 series.
CL           St John's NF to Sydney CB.
CM         Capetown Military, Capetown - Kilindini -Aden
CN          Capetown Northward to dispersal.
CNF        Special designation for Sicily invasion.
CO          Newcastle, NSW to Melbourne & Adelaide in  1942.
COC        Late 1944 early 1945 Plymouth to Brittany series.
CP           Curacao to Panama, 1942 series.
CRD        Casablanca to Dakar.
CT           UK to Canada troopship series in 1941.
CT           Corsica-Sardinia-Bizerta series in 1944.
CU          Curacao-UK tanker series, New York to UK    after CU 3,
CV           Cyrenaica to Valetta, rarely used, 1944.
CW         Cristobal to Key West.
CW         Channel Westward i.e. Southend to St Helens Roads.
CX          Colombo to Addu Atoll, both outward and return passages .
CZ           Curacao to Cristobal (Canal Zone).
DTOP
D             Dakar to Casablanca.
DB          Dikson to White Sea from 1942, new numeration for each year.
DBF        Dakar-Bathurst-Freetown, 1943 series.
DC          Durban to Capetown.
DF           Clyde to Faroes, military ferry service.
DG          Thursday Island to Merauke, New Guinea.
DK          Durban to Kilindini.
DKA       Durban-Kilindini-Aden .
DLM       Durban to I,ourenco Marques.
DM         Durban to Malaya, 1941-42, three convoys only.
DN          Durban Northwards to dispersal.
DR          Dakar to Gibraltar, 1944 series.
DRC        Dakar to Casablanca.
DS           Clyde to Reykjavik, military ferry service.
DSF        Dakar to Freetown.
DSL        Dakar to Freetown & Lagos.
DSP        Dakar to Freetown & Pointe Noire.
DST        Dakar to Freetown & Takoradi.
DT          Danuin to Thursday Island.
DWI       Dutch West Indies to UK, proposed in 1943, not used.
ETOP
E              Trinidad to dispersal southward.
EBC        Bristol Channel coastal convoy to France June to Oct 1944.
EBM       Bristol Channel MT convoy to France June 1944.
EC           Southend to Oban via Firth of Forth, 1941.
ECM       Falmouth to France June/early July 1944.
ECP         Portland & Solent Personnel convoys to Seine Bay June to Oct 1944.
EMM      Two convoys Belfast to France June-July 1944.
EMP       Two personnel convoys Belfast to France July 1944.
EN           Methil to Oban via Loch Ewe .Two series, interrupted by EC.
EPM       Portland to France via Solent MT convoys July to Sept 1944.
EPP         Portland to France via Solent personnel convoys July to Sept 1944.
ET           North Africa to Gibraltar, Nov 1942 to early 1943.
ETC        Thames to France coaster convoys June to Oct 1944.
ETM       Thames to France MT convoys June to Oct 1944.
EWC       Spithead to Normandy beaches, coaster convoys June 1944
EWL       Isle of Wight to France convoys, mainly landing ships & craft June 1944.
EWM     Isle of Wight to France MT convoys Sept and Oct 1944.
EWP       Isle of Wight to France personnel convoys.
EXP        June to Oct 1944 invasion series.
FTOP
FB           Freetown to Bahia, Brazil.
FBC        Seine Bay to Bristol Channel coaster convoys June to Oct 1944.
FD           Faroes to Clyde, military ferry.
FC           France to W of England convoy series June-July 1944.
FCP         France to W of England personnel convoys June-July 1944.
FFT         Freetown to Trinidad 1942 to 1943.
FG           Fremantle to Adelaide, 1942 onward.
FH           Saint John NE to Halifax, late 1942 onward.
FJ            Florianopolis to Rio de Janeiro.
FM          Milne Bay to Port Moresby.
FN           Forth North, Thames to Firth of Forth 1939 to 1945.
FP           Troop convoys to Norway Apr/May 1940.
FPM       France to Portland MT convoys, invasion      series.
FPP         France to Portland personnel convoys July-Aug 1944.
FS           Forth South, Firth of Forth to Thames 1939 to 1945.
FSD        Freetown to Dakar, small craft 1944.
FTC        France to Thames coaster  convoys 1944.
FTM       France to Thames MT convoys 1944.
FWC       France to Isle of Wight coaster convoys June 1944.
FWL       France to Isle of Wight landing craft convoys 1944.
FWM     France to Isle of Wight MT convoys June-July 1944.
FWP       France to Isle of Wight personnel convoys June-Sept 1944.
FXP        France to UK invasion series June to Oct 1944.
GTOP
G             Guantanamo to San Juan PR.
GAT       Guantanamo-Aruba Trinidad.
GB           New Guinea to Milne Bay.
GC           Gibraltar to Casablanca.
GD          Merauke to Thursday Island.
GF           Adelaide to Fremantle.
GI            New Guinea to Philippines.
GJ            Guantanamo to Kingston, Jamaica.
GK          Guantanamo to Key West.
GM         Gibraltar to Malta.
GM         Galveston to Mississippi.
GN          Guantanamo to New York City.
GP           Guantanamo to Panama.
GP           Sydney NSW to Townsville and Brisbane.
"Green"  Gibraltar to Fort Said, late 1933.
"GREYBACK"  Dieppe-Newhaven ferry service.
GS           Greenland to Sydney CB or St John's NE
GS           Humber (Grimsby) to Southend 1940.
GT           Gladstone to Townsville.
GTX        Gibraltar-Tripoli-Alexandria 1943 only.
GUF        Oran or Naples to USA Fast.
GUS        Port Said to USA Slow.
GZ           Guantanamo to Canal Zone 1942 onward.
HTOP
HA          Halifax to Curacao 1942 only.
HA          Heel of Italy to Augusta 1943 onwards.
HE           Troop convoys Australia to India 1945.
HC          Calcutta to Chittagong.
HF           Halifax to Saint John, NE.
HG          Homeward from Gibraltar 1933-42.
HGF        Homeward from Gibraltar Fast.
HHX       Halifax ships joining HX convoys which originated at New York.
HJ           Halifax to St John's, NE
HK          Galveston (Houston) to Key West.
HM         Holyhead to Milford Haven.
HN          Homeward from Norway i.e. Bergen to Methil 1939-40.
HON       Ships joining, from Halifax NS, a NYC-bound ON convoy.
HP           Heel of Italy to Piraeus.
HS           Halifax to Sydney CB.
HT          Halifax to Trinidad preceded HA.
HX          Halifax to UK, later New York City to UK.
HXA       English Channel section of HX 1933-40 & 1944-45.
HXF        Halifax to UK, Fast 1933-40 only.
ITOP
IG            Philippines to New Guinea.
IXF         Italy (Taranto & Naples) to Alexandria & Port Said.
JTOP
JA           Colombo to Aden.
JC            Colombo to Calcutta.
JF            Rio de Janeiro to Florianopolis.
JG            Kingston, Jamaica to Guantanamo.
JH           St John's NF to Halifax NS.
JM          India to Madagascar via Mombassa 1943 only.
JMG        Assault convoy for Malaya Sept 1945.
TN          St John's, NF to Labrador.
JR            Rio de Janeiro to Recife.
JS            Colombo to Singapore Nov 41 to Feb 42.
JT            Rio de Janeiro to Trinidad, 1943-45.
JW          UK to North Russia. Replaced PQ.
KTOP
K             Casablanca to Brest, sometimes suffixed F or S.
KA          Kilindini to Aden.
KB          Kola Inlet to White Sea, fresh numeration annually.
KM         Karachi to Bombay.
KD          Kilindini to Durban.
KG          Key West to Guantanamo.
KH          Key West to Galveston (Houston).
KJ           Kingston, Jamaica to UK, 1940, also KJE
KM         Kilindini to Diego Suarez (Madagascar).
KMF       UK to Mediterranean Fast Nov 1942 onward.
KMS       UK to Mediterranean Slow Nov 1942 onward.
KN          Key West to New York City.
KP           Key West to Pilottown, Mississippi.
KP           Karachi to Persian Gulf.
KP           Kola Inlet to Petsamo 1944-45, fresh numbers annually.
KR          Kilindini to Ceylon.
KR          Calcutta and Arakan ports to Rangoon 1945.
KS           Key West South, i.e. New York to Key West.
KS           Variation on the French K series.
KW         Key West to Havana.
KX          UK to Gibraltar Oct 42 onward.
LTOP
LC           Sydney CB to St John's NE
LE           Levant East i.e. Port Said to Haifa.
LGE         Lagos Eastbound, local West African traffic.
LGW       Lagos Westbound, local West African traffic.
LM          Lagos to Matadi.
LMD       Lourenco Marques to Durban.
LN           St. Lawrence to Labrador.
LQ           Barrier Reef to Brisbane.
LS           Lagos to Freetown.
LSD        Lagos to Dakar via Freetown.
LTS         Lagos-Takoradi- Freetown.
LU           Humber to Elbe, May 1945.
LW         Levant West i.e. Haifa to Port Said.
MTOP
MA         Mombassa to Aden.
MA         Madras to Chittagong 1943.
MB         Colombo to Bombay.
MB         Port Moresby to Fall River.
MC         Aden-Mombassa- Durban- Capetown.
MD         Madagascar to Durban, one convoy only.
ME          Malta East, i.e. Malta to Alexandria  & Port    Said.
MF          Port Moresby to Milne Bay & Fall River.
MG         Malta to Gibraltar.
MG         Mississippi to Galveston.
MH         Milford Haven to Holyhead.
MK         Madagascar to Kilindini.
MKF       Mediterranean to UK Fast Nov 1942 onward.
MKS       Mediterranean to UK Slow Nov 1942 onward.
MN         Mauritius to Seychelles.
MO         Marseilles to North Africa.
MR         Madras to Rangoon.
MS          Melbourne to Singapore Nov 41 to Feb 42.
MS          Marseilles to Naples 1944 to 1945.
MT         Methil to Tyne 1940 & 1941.
MT         Port Moresby to Townsville 1942.
MTC       Seine Bay to Southend, replacing FTC.
MTM     Seine Bay to Southend, replacing FTM.
MV         Milne Bay to Townsville.
MW        Malta Westward, Alexandria to Malta.
NTOP
NA          Canada to UK troop convoys.
NA          Langemak Bay, New Guinea to Admiralty Islands.
NAP       A southbound series, mainly from Dover to France Dec 44.
NE           New Guinea to New Britain.
NC          Walvis Bay to Capetown 1943.
NCF        Fast Sicily invasion convoys 1943.
NCS        Slow Sicily invasion convoys 1943.
NE           New Zealand to Panama.
NG          New York City to Guantanamo.
NJ           Newfoundland coast to St John's  NE
NK          New York City to Key West.
NL           Labrador to St Lawrence.
NLY        Lingayen/Hollandia/Leyte convoys.
NP           Norwegian troop convoys Apr-May 1940.
NP           Turkey to Port Said.
NR          Norway to Methil, 1945.
NS           New Caledonia to Sydney NSW
NSF        North African ports to Naples, troop convoys.
NT          New Guinea to Townsville.
NV          Naples to Augusta.
NYC        New York City to UK via Bermuda & E Coast USA ports.
OTOP
OA          Thames to Liverpool, with an Atlantic element 1939 to July 1940. 
OA          After July 1940,  Methil to Liverpool  to disperse in North  Atlantic.
OB          Liverpool outward, usually joined by the OA of same number.
OC          Melbourne to Newcastle, NSW.
OG          Outward to Gibraltar from  UK.
OM         Oran to Marseilles, 1944 series.
ON          Outward to Norway, Methil to Bergen, in 1939-40.
ON          Outward North. Liverpool etc. to North America 1941 onwards.
ON(F)     Alternate convoys of the ON sequence (see above).
ON(S)     Alternate convoys of the ON sequence (see above).
ONS        Outward North Slow, Liverpool etc to North America 1943 onwards.
OS           Outward Southbound, Liverpool etc to Freetown 1941 onwards.
OSS        Southward extension of OS from Freetown.
OT          Outward Trinidad. Two series, one local Caribbean, one to North Africa.
OW         Outward Westward, Australia-India, numbers re-used.
PTOP
PA          Persian Gulf to Aden.
PB           Persian Gulf to Bombay.
PG           Brisbane to Sydney NSW.
PG           Panama to Guantanamo, 1942 series.
PGE         Pointe Noire southward, local traffic.
PH           Piraeus to Heel of Italy.
PK           Pilottown, Mississippi to Key West.
PN           Port Said Northbound to Turkey.
PQ           Iceland to North Russia, 1941 and 1942.
PQ           Townsville to Port Moresby 1942.
PR           Piraeus to Rabbit Island (Dardanelles), 1945.
PAD        Pointe Noire-Freetown-Dakar.
PT           Paramaribo to Trinidad.
PT           Pearl Harbor to Tarawa.
PTS         Pointe Noire-Takoradi-Freetown .
PV           Melbourne to Townsville.
PW         Portsmouth-Wales.
QTOP
QL           Brisbane to Townsville.
QP           North Russia to Iceland 1941-42.
QS           Quebec to Sydney CB.
RTOP
RA          North Russia to Iceland, later UK 1942-45. Replaced QP
RE           A single convoy of small passenger liners USA to UK 1942.
"Red"     Early Gibraltar to Far East convoy.
RJ            Recife to Rio de Janeiro.
RK          Rangoon to Arakan and Calcutta, 1945.
RK          Colombo to Kilindini, 1944.
RM         Rangoon-Madras-Colombo, 1945.
RN          Methil to Norway, May 1945.
RP           Dardanelles (Rabbit Island) to Piraeus, 1945.
RS           Gibraltar to Freetown 1943.
RT           Capetown to Freetown, 1941.
RT           Recife to Trinidad, 1943.
RU          Reykjavik to Loch Ewe, later Belfast. 1941-45.
STOP
SB           Sydney CB to Corner Brook from 1942.
SBF       Assault convoys for Sicily invasion.
SBM      Assault convoys for Sicily invasion.
SC           Sydney CB later Halifax or New York to UK. Commenced 1941.
SD           Iceland to Clyde, military ferry service.
SD           Seychelles to Diego Suarez, 1944.
SG           Southend to Humber (Grimsby) 1940.
SG           Sydney CB later St John's NF to Greenland, 1942 onwards.
SH           Sydney CB to Halifax.
SHX        Sydney CB component joining HX convoys.
"SILVERTIP"  Newhaven-Dieppe ferry service.
SJ            San Juan PR to Guantanamo.
SJ            Singapore to Colombo, Nov 41 to Feb 42.
SJ            Santos to Rio de Janeiro.
SL           Freetown to UK.
SLF         Freetown to UK Fast.
SLS         Freetown to UK Slow.
SM          Batavia to Fremantle, Dec 41 to Feb 42.
SM          Naples to Marseilles, 1944.
SN           Sydney NSW to New Caledonia.
SNF        South from Naples, Fast troopships Naples to North Africa.
SQ           Sydney CB to Quebec.
SR           Sandheads (Calcutta) to Rangoon 1941-42.
SR           Freetown to Gibraltar 1943-44.
ST           Freetown to Takoradi.
ST           Sydney NSW to Townsville 1')43.
STC        Freetown-Takoradi-Capetown .
STL         Freetown-Takoradi-Lagos.
STP         Freetown-Takoradi-Pointe Noire.
STW       Freetown-Takoradi-WaIvis Bay.
SU           Suez to Australia 1940-41.
SV           Sydney NSW to Townsville.
SW         Suez to Mombassa or Durban, 1940-41.
TTOP
T             Hollandia to Manila.
TA          UK to USA, large troopships.
TA          Tobruk to Alexandria.
TAC       Thames to Ostend 1945.
TACA    Thames to Antwerp, later retitled TAM.
TAG       Trinidad-Aruba-Guantanamo 1942 onwards.
TAM      Thames to Antwerp Military, retitled from TAC qv.
TAP        Thames to France 1945.
TAW      Trinidad-Curacao-Key West 1942.
TB           Trinidad to Bahia, Brazil.
TBC        Thames to Bristol Channel, 1944-45.
TC           Troops from Canada, troop convoys to UK 1933-41.
TC           Tunisia to Corsica, 1943-44.
TCU        Occasional CU convoys containing troopships.
TD          Thursday Island to Darwin.
TD          New Zealand to Northern Australia.
TE           Trinidad Eastward to dispersal.
TE           Torch Eastward,   Gibraltar to North Africa 1942-43.
TF           Trinidad to Freetown.
TG           Trinidad to Guantanamo.
TGE        Takoradi, Lagos  Eastward to dispersal.
TH          Trinidad to Haiifax 1942.
TJ           Trinidad to Rio de Janeiro.
TJF       Assault  convoys for Sicilian invasion.
TJM      Assault  convoys for Sicilian invasion.
TJS       Assault  convoys for Sicilian invasion.
TLDM    Takoradi-Lagos-Duala-Matadi.
TM         Norwegian troop convoys Apr-May 1940 only.
TM         Trinidad to Mediterranean 1942.
TMC       The retitled ETC series-qv.
TMM     The retitled ETM series-qv.
TN          TownsviIle to New Guinea.
TO          North Africa to Caribbean.
TO          Trinidad to Curacao.
TP           Troop convoy from Norway to UK May 1940.
TP           Trinidad to Paramaribo.
TP           Tarawa to Pearl Harbor.
TR           Trinidad to Recife.
"TRINIDAD" Trinidad to dispersal southeast.
TS           Takoradi to Freetown.
TS           Townsville to Sydney NSW & Brisbane.
TSD        Takoradi-Freetown-Dakar
TSF       Assault  convoys for Naples landings.
TSM     Assault  convoys for Naples landings.
TSS      Assault  convoys for Naples landings.
TU          UK to USA military convoys, reversal of UT.
TV           Tripoli (Libya) to Valetta.
TX          Tripoli (Libya) to Alexandria.
UTOP
UA          UK to Azores, three convoys to occupy the islands in 1943.
UC          UK to New York,  reversal of CU.  Occasionally a T suffix.
UGF        USA to Gibraltar, later Naples, started Nov 1942.
UGL        USA to Gibraltar, landing craft convoys.
UGS        USA to Gibraltar, later Port Said Nov 42-May 45.
UL           Elbe to Humber post May 1945.
UR          Loch Ewe (later Belfast) to Reykjavik (Iceland),
US           Australia to Suez. US 3 diverted to UK via Cape.
UT          USA to UK troop convoys 1943-44.
VTOP
VB           Townsville to Brisbane.
VC           Valetta to Cyrenaica 1943-44.
VK          Sydney NSW to Wellington.
VN          Augusta to Naples, also used for Malta to Naples, late 1944 Naples to Leghorn
VS           Townsville to Sydney NSW.
VT           Valetta to Tripoli, Libya.
WTOP
WA        Curacao to Aruba. Oct to Dec 1944 invasion series.
WAT      Key West- Curacao-Trinidad.
WDC      Sept to Dec 1944 invasion series.
WEC       Isle of Wight to France Dec 1944 to May 1945.
WEL       Isle of Wight to France, landing craft 1944-45.
WEP       Isle of Wight to Cherbourg series, Dec 1944.
WFM     Oct and Nov 1944 invasion series.
WMP     Isle of Wight to Arromanches Nov & Dec 1944.
WN         Clyde, Oban & Loch Ewe to Firth of Forth.
WNC      Isle of Wight to Havre Dec 1944 to May 1945.
WNL      Isle of Wight to France Apr to May 1945.
WO         India to Australia troop convoys.
WP         Wales-Portsmouth i.e. Milford Haven to Solent.
WS         Wabana to Sydney CB.
WS         UK to Suez and Bombay, troop convoys 1940-43.
WTS       Walvis Bay-Takoradi-Freetown.
WVP       Isle of Wight to France Dec 1944 to May 1945.
WX         Western Desert ports to Alexandria.
XTOP
XB          Halifax to Boston.
XIF         Alexandria & Fort Said-Italy (Taranto & Naples).
XK          Gibraltar to UK.
XT          Alexandria to Tripoli (Libya).
XTG        Alexandria-Tripoli-Gibraltar 1943 only.
XW         Alexandria to Western Desert ports.
ZTOP
ZC           Cristobel to Curacao.
ZG           Cristobel to Guantanamo.
ZT           New Zealand to Sydney NSW.