Overview of ISO/ANSI label processing
Label processing is handled by the I/O support routines of data
management (open, EOV, and close). Label processing consists of the
following basic functions:
- Converting input labels from ASCII to EBCDIC and converting output labels from EBCDIC to ASCII
- Checking the labels on input tapes to
- Ensure that the correct volume is mounted
- Identify, describe, and protect the data set being processed
- Attempt to ensure maximum correctness and consistency of data sets and their labels
- Identify compatibility conflicts with Version 3 or Version 4 standards
- Checking the existing labels on output tapes to
- Ensure that the correct volume is mounted
- Prevent overwriting of vital data
- Identify compatibility conflicts with Version 3 or Version 4 standards
- Creating and writing new labels on output tape
- For volumes in an automated tape library, comparing the external volume serial number to the magnetically recorded internal label.
These processing functions are summarized in Table 1. The table shows the specific labels that are processed for each function and which routines perform the functions.
Although the default of each IBM-supplied installation exit is to reject the volume, the exits can be modified to do additional label processing. See ISO/ANSI installation exits for more information.
All volumes will be written with Version 3 or Version 4 labels. For information about using tapes with other than Version 3 or Version 4 labels, see Compatibility with non-version 3 or non-version 4 volumes.
Processing | Volume Label | Header Labels1 | Trailer Labels1 | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
VOL1 | VOL 2–9 | User Volume Labels | HDR1 | HDR2 | HDR3-9 | UHL | EOF1 or EOV1 | EOF2 or EOV2 | EOF3-9 or EOV3-9 | UTL | |
First or only volume2 | |||||||||||
Checks labels on input tape | Open | Ignored3 | Ignored3 | Open | Open | Ignored3 | Open | EOV | Bypassed | Ignored3 | EOV |
Checks existing labels on output tape before overwriting | Open | Ignored4 | Ignored4 | Open | Not read | Not read | Not read | Not read | Not read | Open | |
Writes new labels on output tape | Open or user5 | Not written | Not written | Open | Open | Not written | Open | Close or EOV | Close or EOV | Not written | Close or EOV |
Compares the volume serial number on the external volume label to the serial number in the tape volume label7 | Open | N/A8 | N/A8 | N/A8 | N/A8 | N/A8 | N/A8 | N/A8 | N/A8 | N/A8 | N/A8 |
Second or subsequent volumes6 | |||||||||||
Checks labels on input tape. | EOV | Ignored3 | Ignored3 | EOV | Bypassed | Ignored3 | EOV | EOV | Bypassed | Ignored3 | EOV |
Checks existing labels on output tape before overwriting. | EOV | Ignored4 | Ignored4 | EOV | Not read | Not read | Not read | Not read | Not read | Not read | Not read |
Writes new labels on output tape. | EOV or user5 | Not written | Not written | EOV | EOV | Not written | EOV | Close or EOV | Close or EOV | Not written | Not written |
Compares the volume serial number on the external volume label to the serial number in the tape volume label7 | EOV | N/A8 | N/A8 | N/A8 | N/A8 | N/A8 | N/A8 | N/A8 | N/A8 | N/A8 | N/A8 |
Notes:
|