API : Advance Passenger Information
APP : Advance Passenger Processing or Also called APPS (Advance Passenger Processing System)
PNR : Passenger Name Record
PNRGOV : A full PNR data that is required by the Governments, Regulators or Airport authorities in advance of flight departure or flight arrival
DCS : Departure Control System is normally have message with identifier of PRL.
Usually when one flight closed on DCS it used to send following 12 messages