PFRX means Preflight Relmat X-1,2,3...9 or A,B,C...Z in NASA
Similar to PFRX
ACC - Aft Cargo CarrierACCA - Automatic Cloud Cover Assessment
ACCMS - Advanced Checkout, Control, and Maintenance System
ACCS - Advanced Checkout and Control System
ACE - Advanced Composition Explorer
ACE - Apollo Checkout Equipment
ACES - Acoustic Containerless Experiment System
View all in NASA