David RossDavid Ross 522 bronze badges 1 one The SUB is surely an artefact of CP/M, where it absolutely was utilised being an EOF marker (CP/M "length" was blocks, not bytes). MSDOS was created in order to go through CP/M data files, & since it was likely at the time that CP/M would be utilized to go through the resuts from MSDOS, the opportunity t