trigram) Prinair - Puerto Rico International Airlines PRK – (s) Democratic People's Republic of Korea (ISO 3166 trigram) PRM – (i) Personnel Readiness Management PRN – (i) pro re nata (Latin, "for the emergency", "as needed") PRT (s) Portugal (ISO 3166 trigram) (i) Provincial Reconstruction Team PRY – (s) Paraguay (ISO 3166 trigram) PS ps (s) Pashto language (ISO 639-1 code) picosecond pS – (s) picosiemens Ps – (s) petasecond PS (s) Palestinian Territory, Occupied (ISO 3166 digram) (i) Personnel Services (s) petasiemens (i) post scriptum (Latin, "written after") Power Steering Power Supply Public School PooS – Poo Sniffer (Internet shorthand) PSA (i) Paralysis Society of America Pharmaceutical Society of Australia Pressure-Sensitive Adhesive Production Services Association Prostate Specific Antigen Public Service Announcement Public Service Association PSC (i) Personal service corporation Primary Somatosensory Cortex PSE – (s) Palestinian Territory, Occupied (ISO 3166 trigram) PSG (i) Pacific Seabird Group Paris Saint-Germain PSI - (i) Pounds per square inch PSI – (a/i) Portable Source Initiative PSO (i) Peace Support Operations Primary Standardisation Office (ABCA) Protocol Supporting Organization (of the ICANN) PSS – (i) Personnel System Support PST – (i) Pacific Standard Time (UTC−8 hours) PSU – (i) Pennsylvania State University PSV (i) Philips Sport Vereniging (Dutch for "Philips Sports Union") Public Service Vehicle PsyOp – (p) Psychological Operations PT pt – (s) Portuguese language (ISO 639-1 code) pT – (s) picotesla Pt – (s) Platinum PT – (s) petatesla – (i) Physical Training (in the Army) – (s) Portugal (ISO 3166 digram) PTA – (i) Parent-Teacher Association PTAL – (i) Public Transport Accessibility Level PTAN – (i) Precision Terrain Aided Navigation (a) (pronounced P-tan) Provider Transaction Access Number PTCAS - Physical Therapy Centralized Application System PTES - (i) People's Trust for Endangered Species PTFE – (i) PolyTetraFluoroEthylene PTI – (i) Pardon the Interruption PTL – (p) Patrol – (i) Primary Target Line PTO – (i) Patent and Trademark Office – Please Turn Over PTSD – (i) Posttraumatic stress disorder PTUI – (a/i) Plain-Text User Interface ("pa-too-ey") (cf CLI) PU Pu – (s) Plutonium PU (s) Guinea-Bissau (FIPS 10-4 country code) (i) Polyurethane (s) United States Miscellaneous Pacific Islands (ISO 3166 digram; obsolete 1986) Pub – (p) Publication PUG – (a/i) PET Users Group PUN – (a/i) Pull-Up Network PUP – (a/i) Pull-Up Point PUR – (s) Puerto Rico (IOC and FIFA trigram, but not ISO 3166) pus – (s) Pashto language (ISO 639-2