{HEAD ~ This invention} relates to {TAIL ~ the field} of optical taggants and more specifically, to materials and methods for tagging explosives and propellants for forensic identification, quality control, and other purposes 
relates to
{ HEAD ~ This invention } relates to { TAIL ~ the field } of optical taggants and more specifically , to materials and methods for tagging explosives and propellants for forensic identification , quality control , and other purposes
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