Format of the ISO/ANSI volume label (VOL1)
Figure 1 shows the format of the ISO/ANSI volume label. The shaded areas represent fields that are recorded in the label, but not used or verified during processing. The contents and processing of each field of the label are described, as are differences between the ISO/ANSI volume label and the IBM volume label.
Figure 1. Format of the ISO/ANSI volume label
1—Label Identifier (3 bytes)
- Contents: The characters VOL identify this label as a volume label.
- Processing: This field is read to verify that a standard
labeled tape is mounted, and that this label is a volume label.
The labels are created by the EDGINERS or IEHINITT utility programs.
In the following situations, the Open or EOV routines create a Version 3 or Version 4 volume label based on specifications in your DD statement:- If you request a Version 3 or Version 4 output volume (AL, AUL) without specifying a volume serial number, and an NL, NSL, or SL labeled volume is mounted to satisfy your request
- If you request a Version 3 or Version 4 output volume (AL, AUL) without specifying a volume serial number, and a volume that can be overwritten and recorded in the wrong density is mounted to satisfy your request (only if output is for the first data set on the volume).
For ISO/ANSI labeled tape volume requests, DFSMSrmm or the label anomaly installation exit routine or label editor installation exit routine can give permission for OPEN or EOV to write or rewrite the VOL1 label. See ISO/ANSI volume label verification and editor routines for more information.
2—Label Number (1 byte)
- Contents: The relative position of this label within a set of labels of the same type; it is always 1 for the Version 3 or Version 4 volume label.
- Processing: Verified in conjunction with Field 1 to identify this label as VOL1.
3—Volume Identifier (6 bytes)
- Contents: A unique identification code, known in the system
as the volume serial number, assigned through JCL, DFSMSrmm, or IEHINITT
to the volume when it enters the system, or assigned by the operator
when Open or EOV routines label the volume. This code might also appear
on the external surface of the volume for visual identification. The
code is typically numeric (000000 to 999999), but can be from 1 to
6 characters long. If the code is less than 6 characters, it is left-justified
and padded with blanks.
All national characters and some special characters in this field are rejected during open as invalid ASCII characters. For a list of the valid ASCII characters, see Label definition and organization.
- Processing: When the user specifies a volume serial number,
it is in the JFCB. The system copies it to the UCB. When
the system processes the labels, it compares the number in the UCB
to the number in this field of the label to ensure that the correct
volume is mounted.
For scratch output tapes, the volume serial number is obtained from this field of the label and recorded in both the JFCB and the UCB.
- Difference from IBM Field: The corresponding field in an IBM standard label is called the Volume Serial Number.
4—Accessibility (1 byte)
- Contents: A valid Version 3 or Version 4 character indicates that the RACHECK installation exits are entered and receive accessibility parameters, or the volume access exit will be entered in order to accept or reject the volume. A space indicates that the volume is authorized for access, unless RACF rejects the volume. All other characters cause the volume to be rejected if the volume is not defined to RACF.
- Processing: If this field contains any invalid Version 3 or Version 4 characters, then the volume is rejected by the system, unless the volume has been defined to RACF.
- Difference from IBM Field: The corresponding field in an IBM standard label is reserved and currently unused.
5—Reserved for Future Standardization (13 bytes)
- Contents: Reserved for possible future use and recorded as blanks.
- Processing: Not used or verified, except to check for all blanks. The EDGINERS and IEHINITT utility programs write blanks in this field. (Blanks are translated to ASCII space characters on output.)
6—Implementation Identifier (13 bytes)
- Contents: Reserved for possible future use and recorded as blanks.
- Processing: Not used or verified, except to check for all blanks. The EDGINERS and IEHINITT utility programs write blanks in this field. (Blanks are translated to ASCII space characters on output.)
7—Owner Identifier (14 bytes)
- Contents: Indicates a specific customer, person, installation, department, and so forth, to which the volume belongs. Any code or name is acceptable.
- Processing: Not used or verified, except to check for valid Version 3 or Version 4 characters. The EDGINERS and IEHINITT utility programs write the text specified by the user, and the open and EOV routines write the text specified by the operator. If the code is less than 14 bytes long, it is left-justified and the remainder of the field is padded with blanks. (Blanks are translated to ASCII space characters on output.)
- Difference from IBM Field: The corresponding field on an IBM standard label is 10 bytes long.
8—Reserved for Future Standardization (28 bytes)
- Contents: Reserved for possible future use and recorded as blanks.
- Processing: Not used or verified, except to check for all blanks. The EDGINERS and IEHINITT utility programs write blanks in this field. (Blanks are translated to ISCII/ASCII space characters on output.)
9—Label Standard Level (1 byte)
- Contents: 3 signifies that the tape is formatted according to Version 3 interchange standards. 4 signifies that the tape is formatted according to Version 4 interchange standards.
- Processing: The operating system always places 3 or 4 in this field on output. Version 1 tapes contain 1 in this field and are accepted for input processing. The system rejects any character other than 1, 3, or 4 in this field.
- Difference from IBM Field: This field is blank in IBM standard labels.