Can anybody point me in the direction of some documentation that can help me to distinguish between these two fuels? I have been searching for hours and I keep coming across articles that use these as sample fuels in experiments, but none that actually describes the numbering convention? I understand that JP-8 Jet A + additives, but what are the differences between the JP-8's themselves? I have also see it as JP-8 POSF 3773 and JP-8 POSF 4177. Any help is appreciated.