(PARs) An IBM proprietary large scale airline reservation application, executing under the control of IBM' sACP (and later itssuccessor, TPF). In the early days of automated reservationssystems in the 1960s and 1970s the combination of ACP and PARs provided unprecendented scale and performance from an on-line real-timesystem, and for a considerable period ranked among the largest networks and systems of the era. IPARs was the international version. (1999-01-18)