Advance Passenger Information filing: carriers must use a prescribed flat-file API format with specific delimited fields and null protocols. Carriers must transmit separate passenger and crew API flat files using a prescribed filename convention and a fixed sequence of pipe-delimited fields covering flight identifiers, travel document particulars, personal and contact information, crew license details, and visa data; null values are required where data are unavailable, each passenger record is single-line, passport may be optional for certain nationalities, and submission may alternatively follow the UN/EDIFACT PAXLST API implementation guide.