A combined file is both an input file and an output file. When a combined file is processed, the output record contains only the data represented by the fields in the output record. This differs from an update file, where the output record contains the input record modified by the fields in the output record.
A combined file is valid for a SPECIAL or WORKSTN file. A combined file is also valid for a DISK or SEQ file if position 18 contains T (an array or table replacement file).