What does P..R stand for?

What does P..R mean?

PR	partial response Medical
PR	Problem Report Governmental » Military
PR	Preliminary Review Governmental » Military
PR	Pair Governmental » Military
PR	Person Responsible Governmental » Military
PR	Photo Reconnaissance Governmental » Military
PR	Picatinny Rail Governmental » Military
PR	Personnel Recovery Governmental » Military
PR	Phoenix Raven Governmental » Military
PR	Primary Zone Governmental » Military
PR	Production Requirement Governmental » Military
PR	Program Review Governmental » Military
PR	Pork Recordings Community » Music
PR	Punk Rock Community » Music
PR	Purchase Request Governmental » NASA
PR	Pulse Rate Governmental » NASA
PR	Public Relations Governmental » NASA
PR	Procurement Regulation Governmental » NASA
PR	Problem Report Governmental » NASA
PR	PRimary Governmental » NASA
PR	Pressure Regulator Governmental » NASA
PR	Pressure Ratio Governmental » NASA
PR	Position Record Governmental » NASA
PR	Performance Report Governmental » NASA
PR	Payload Recorder Governmental » NASA