Chemical weapon designation Chemical , biological , and radiological warfare agents are sometimes assigned what is termed a military symbol . 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 are sometimes applied as marking on weapons to indicate the agent contents . Military symbols constantly change and have 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 England , 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 Sunshine . 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 agent s a 1 signifies micropulverized ( e . g . , CS1 ) , and a 2 signified microencapsulated ( e . g . , CS2 ) . With biological agent s a 1 signifies a wet - type agent ( e . g . , UL1 ) , and a 2 signifies a dry - type agent ( e . g . , UL2 ) . Binary chemical weapon s 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 - 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 :