filaments (aggregations of tau proteins in the human brain associated with tauopathy) Potentially Hazardous Food Premier Hockey Federation (North American women's ice hockey league) PHL – (s) Philippines (ISO 3166 trigram) PHQ - Patient Health Questionnaire PHP (s) Philippine peso (ISO 4217 currency code) (i) PHP: Hypertext Preprocessor (originally Personal Home Page (Tools)) PI pi – (s) Pāli language (ISO 639-1 code) Pi – (s) Pebi PI – (i) PolyImide – PolyIsoprene – Private Investigator PIB – (i) PolyIsoButylene PIC – (i) Person In Charge PICNIC – (a) Problem In Chair Not In Computer PICS – (i) Private Investment Capital Subscription PID – (i) Pelvic Inflammatory Disease – (p) Plan Identification Number – Positive Identification – Procedural Identification – (i) Procurement Identification Description PIDOOMA – (a/i) Pulled It Directly Out Of My Ass PIF – (a/i) Partners in Flight PIG – (a) Pipeline Inspection Gauge PIGS (also PIIGS or PIIGGS) – (a) Portugal, Italy, Greece, Spain; PIIGS if including Ireland; PIIGGS if including the United Kingdom (Great Britain) PIGS – Passenger Inert Guidance Systems – Movable tape barrier, typically used on airport aprons to guide passengers to/from their aircraft avoiding danger areas. PIM – (a/i) Parameterized Ionospheric Model – Path of Intended Motion – Pediatric Index of Mortality – Personal Information Manager/Management – Presence and Interworking Mobility – Processor-In-Memory – Program Integration Manager – Protocol Independent Multicast PIN – (a) Personal Identification Number PINF – (i) People In Need Foundation (Czech charitable organisation) PIPA – (a/i) Program on International Policy Attitudes PIR – (i) Priority Intelligence Requirement PIRA – (a) Provisional Irish Republican Army PIREPS – (p) Pilot Reports PITA – (a) Pain In The Ass P.I. - Philippines Islands PITS - Person In The Seat. A common problem as to why a computer is not working properly. It is a PITS issue. PJ pJ – (s) picojoule PJ – (s) petajoule PJHQ – (p) Permanent Joint Headquarters PJs – (p) Pajamas ("pee-jayz") PK K – (s) picokelvin PK – (s) Pakistan (ISO 3166 and FIPS 10-4 country code digram) – petakelvin – (i) Player Kill[er] – Probability of Kill – (p) PolyKetone – (i) Pulemet Kalashnikova (Russian ПК пулемет Калашникова, "Machinegun Kalashnikov") PKA – (i) previously known as – professionally known as PKE – (i) Partnership of Kindermusik Educators PKI – (i) public key infrastructure (cryptography) PKM – (i) Pulemet Kalashnikova Modernizirovanniy (Russian ПКМ пулемет Калашникова модернизированный, "Machinegun Kalashnikov