1) Addendum of a sort 2) Additional afterthought 3) Additions to letters 4) Afterthought number 2 5) Afterthought on a letter 6) Epistolary afterthoughts 7) Last thought in a ltr 8) Letter addenda 9) Letter addendum 10) Letter addition letters 11) Letter additions 12) Letter adjunct 13) Letter afterthoughts 
abbreviation: pulse per second (see also prr)
protecte payments system
Parent Partnership Service
Prospective Payment System
Pay Per SalePay-Per-Sale - Where a commission is paid for each sale generated by an affiliate. The commission is usually a percentage of the sale, although sometimes it's a fixed amount.
Packets Per Second + Power Personal Systems [IBM]
Pulses per secondSee 'Polyphenylene Sulfide'
Petrol Points
Pitch Plane Scan
Post-polio syndrome
Prospective Payment System
Precise Positioning Service
post postscriptum; PPS Written after that which was previously written afterward. That which is written after a previous post script as an additional after thought.
Passenger Presence Sensor
pulse per second.