Chemical, biological (CB) — and sometimes radiological — warfare agents were assigned what is termed a military symbol by the U.S. military until the American chemical and biological weapons programs were terminated (in 1990 and 1969, respectively).
Military symbols applied to the CB agent fill, and not to the entire weapon.
A chemical or biological weapon designation would be, for example, "Aero-14/B", which could be filled with GB, VX, TGB, or with a biological modification kit – OU, NU, UL, etc.
A CB weapon is an integrated device of (1) agent, (2) dissemination means, and (3) delivery system.
Military symbols evolved out of the First World War from the British in part for secrecy, and to simplify reference to chemicals by something other than a chemical name.
These symbols were sometimes applied as marking on weapons to indicate the agent contents.
Military symbols constantly changed and had transitory definitions.
For example, mustard gas was assigned the military symbol originally HS for "Hun Stuff".
Later in the First World War the S in HS signified mustard gas that had about 25% solvent added to it.
This was only in the United Kingdom, as HS was adopted as the military symbol by the United States – signifying crude mustard.
In the Second World War the purity of mustard gas was improved through distillation, and this purified chemical warfare agent was designated HD.
When it was mixed with a thickener (Agent VV), it was given the symbol HV.
Today mustard gas is indicated by the single capital letter H, but HD is still in common use.
Military symbols can also reflect the name of where a chemical agent is manufactured.
For example, chloropicrin has the symbol PS, which was derived from the British town in which it was manufactured during the First World War: Port Sunlight.
Another device in assigning military symbols is in honor of the person that had devised the agent, such as Agent TZ (saxitoxin), which was derived after the name of its principal investigator, Dr. Edward Shantz.
Numbers are occasionally added to military symbols to reflect particular preparations.
With riot control agents  a 1 signifies micropulverized (e.g., CS1), and a 2 signified microencapsulated (e.g., CS2).
With biological agents a 1 signifies a wet-type agent (e.g., UL1), and a 2 signifies a dry-type agent (e.g., UL2).
Binary chemical weapons are signified by adding a 2, as in binary sarin (i.e., GB2).
Other formulations have their own designation.
When the Tear Agent CS is formulated in a solvent it is signified by CSX.
When agents are thickened with the addition of a polymer a T is usually added to the beginning of the symbol (e.g., thickened soman is TGD).
The tear agent Mace, or Agent CN, had been formulated in several solvent forms, indicated by CNB (with benzene), CNC (with chloroform), and CNS (with chloropicrin and chloroform).
Mixtures of agents have been identified with either a hyphen (e.g., CN-DM), or combining letters of the two agents (e.g., HD mixed with L is HL).
Furthermore, one strain of the biological agent Tularemia has the symbol SR (lethal Schu strain), while another strain has JT (incapacitant 452 strain).
Military symbols for agents change from time to time for administrative reasons as well.
To preserve secrecy, tularemia's symbol UL1 and UL2 was changed to TT and ZZ at one time, and then later to SR.
During the Second World War cyanogen chloride's symbol was changed from CK to CC, but when it became apparent that CC marked munitions might be mistaken for CG (phosgene), the symbol was changed back.
The following designations are, or have been, used by the United States: Chemical agents
Blood agents
AC – hydrogen cyanide
CK – cyanogen chloride
SA – Arsine
Choking agents
BBC – bromobenzyl cyanide
CL – chlorine
CG – phosgene
DP – diphosgene
KJ – stannic chloride
NC – 80% chloropicrin, 20% stannic chloride
PS – chloropicrin
Z –  zyklon-B
Blister agents
H – mustard gas
HD – distilled mustard gas
T – O-Mustard
Q – sesquimustard
L – Lewisite
HL – mustard-lewisite mixture
HT – mustard-T mixture
HQ – mustard-Q mixture
HN – nitrogen mustard
ED – ethyl dichloroarsine
MD – methyl dichloroarsine
PD – phenyl dichloroarsine
Tear agents
CA – camite
CN – mace
CNB – mace-benzene mixture
CNC – mace-chloroform mixture
CND
CNS – mace-chloropicrin-chloroform mixture
CS – CS gas
CS1 – micropulverized CS
CS2 – microencapsulated CS
CR – CR gas
CH –
Vomiting agents
DA – diphenylchlorarsine
DC – diphenylcyanoarsine
DM – Adamsite
Psycho agents
BZ – 3-quinuclidinyl benzilate
SN – sernyl (PCP)
K – lysergic acid diethylamide (LSD) [EA 1729]
Nerve agents
GA – tabun [EA1205]
GB – sarin [EA1208]
GB2 – sarin as a binary agent from mixing OPA (isopropyl alcohol+isopropyl amine) + DF [EA5823]
GD – soman [EA1210]
GF – cyclosarin [EA1212]
GE – ethyl sarin
GH – O-isopentyl sarin [EA1221]
GS – S-butyl sarin [EA1255]
GV – (dimethylaminoethyl phosphorodimethyl amidoylfluoridate) [EA5365]
VE – VE nerve agent [EA1517]
VG – Amiton (O,O-diethyl-S-[2-(diethylamino)ethyl] phosphorothioate) [EA1508]
VM – Edemo [EA1664]
VS – (O-Ethyl S-2-(diisopropylamino)ethyl ethylphosphonothiolate) [EA1677]Hoenig, Steven L. (2007), Compendium of Chemical Warfare Agents, Springer, pp 106-109,
VP – (3-pyridyl 3,3,5-trimethylcyclohexyl methylphosphonate) [EA1511]US 3903098
VR – VR nerve agent (O-isobutyl S-(2-diethaminoethyl) methylphosphothioate)
VX – VX nerve agent [EA1701]
TZ – Saxitoxin
Experimental agents
Material Testing Program EA (Edgewood Arsenal) numbers:
EA 1152 - Diisopropyl fluorophosphate (DFP)
EA 1205 - Tabun (GA)
EA 1208 - Sarin (GB)
EA 1210 - Soman (GD)
EA 1212 - Cyclosarin (GF)
EA 1221 - O-isopentyl sarin
EA 1255 - S-butyl sarin
EA 1285 - Tetraethyl pyrophosphate (TEPP)
EA 1298 - Methylenedioxyamphetamine (MDA), an analogue and active metabolite of MDMA
EA 1475 - Methylenedioxymethamphetamine
EA 1476 - A dimethylheptylpyran variant ("red oil")
EA 1508 - VG
EA 1517 - VE
EA 1653 - LSD in tartarate form
EA 1664 - Edemo (VM)
EA 1677 - VS, a "V-series" nerve agent
EA 1701 - VX
EA 1729 - LSD in free base form
EA 2092 - Benactyzine
EA 2148-A - Phencyclidine (PCP)
EA 2233 - A dimethylheptylpyran variant
Eight individual isomers numbered EA-2233-1 through EA-2233-8
EA 2277 - BZ ("Substance 78" to Soviets)
EA 3148 - A "V-series" nerve agent, Cyclopentyl S-2-diethylaminoethyl methylphosphonothiolate ("Substance 100A" to Soviets)
EA 3167 - A BZ variant
EA 3443 - A BZ variant
EA 3528 - LSD in malleate form
EA 3580 - A BZ variant
EA 3834 - A BZ variant
EA 5365 - GV
EA 5823 - Sarin (GB) as a binary agent from mixing OPA (isopropyl alcohol+isopropyl amine) + DF
Biological agents
Mycotic biological agents
OC - Coccidioides mycosis
Bacterial biological agents
N - anthrax
TR - anthrax
LE - plague
UL - tularemia (schu S4)
TT - wet-type UL
ZZ - dry-type UL
SR - tularemia
JT - tularemia (425)
HO - cholera
AB - bovine brucellosis
US - porcine brucellosis
NX - porcine brucellosis
AM - caprine brucellosis
BX - caprine brucellosis
Y - bacterial dysentery
LA - Glanders
HI - Melioidosis
DK - diphtheria
TQ - listeriosis
Chlamydial biological agents
SI - psittacosis
Rickettsial biological agents
RI - rocky mountain spotted fever
UY - rocky mountain spotted fever
OU - Q fever
MN - wet-type OU
NT - dry-type OU
YE - human typhus
AV - murine typhus
Viral biological agents
OJ - yellow fever
UT - yellow fever
LU - yellow fever
FA - Rift Valley fever
NU - Venezuelan equine encephalitis virus
TD - Venezuelan Equine Encephalitis virus
FX - Venezuelan Equine Encephalitis virus
ZX - Eastern equine encephalitis virus
ZL - smallpox
AN - Japanese B encephalitis
Biological vectors
AP = Aedes aegypti mosquito
Biological toxins
X - botulinum toxin A
XR - partially purified botulinum toxin A
W - ricin toxin
WA - ricin toxin
UC - staphyloccocal enterotoxin B
PG - staphyloccocal enterotoxin B
TZ - saxitoxin
SS - saxitoxin
PP - tetrodotoxin
Others
Simulants
MR - molasses residuum
BG - Bacillus globigii
BS - Bacillus globigii
U - Bacillus globigii
SM - Serratia marcescens
P - Serratia marcescens
AF - Aspergillus fumigatus mutant C-2
EC - Escherichia coli
BT - Bacillus thuringiensis
EH - Erwinia hebicola
FP - fluorescent particle
Radiological agent
RA -
References
