For Input Files on ANSI or IBM Standard Labeled Tapes:
For end-of-file condition, the EOF1 labels are processed. Among
other things, this processing ensures that the file was read correctly.
After EOF1 processing, the exit routine specified in the DCB gets
control.
For end-of-volume condition, the EOV1 labels are processed for
the current tape volume and tape volume switching occurs.
EOF2 and EOV2 labels are bypassed.
If specified, user trailer labels are processed. You must provide
a routine to do this.