$ZEO[F] contains a truth-valued expression indicating whether the last READ operation reached the end-of-file. $ZEOF equals TRUE (1) at EOF and FALSE (0) at other positions.
GT.M does not maintain $ZEOF for terminal devices.
$ZEOF refers to the end-of-file status of the current device. Therefore, exercise care in sequencing USE commands and references to $ZEOF.
GT.M does not permit the SET or NEW command to modify $ZEOF.
For more information on $ZEOF, refer to the "Input/Output Processing" chapter.