PFRX means Preflight Relmat
X-1,2,3...9 or A,B,C...Z in
NASA
Similar to PFRX
A - Acceleration
A - Aft
A&A - Advertise and Award
A&E - Architectural and Engineering
A&E - Architects and Engineering
A&I - Assembly and Installation
A&L - Approach and Landing
View all in NASA