Presumably it is a file which is intended to be sent (eventually) to a printer process to create a hard copy. Many operating systems (particularly those which are batch-processing oriented) allow the programmer to include control codes within a file to be printed, to control the vertical format of the printed page--for example, single/double line spacing, overprinting, and page ejection. A "print file" is one which includes such vertical format control ("VFC") information. [RFC 448
A print file is a text file created by a MIPS program after processing an image. This file contains information such as: program name, execution date and time, input and output file names and sizes, parameter selections, program specific information and other information such as actual CPU time used and page faults.