INIT Initializing (emulated) magnetic tapes

Version:	INIT V21.0A
Privileges:	TAPE-PROCESSING (for nonprivileged functions) TAPE-PROCESSING (for privileged functions)

The INIT utility routine initializes magnetic tapes (magnetic tape cartridges, MTCs) and emulated magnetic tapes.

Initialization is the process of writing a volume label (VOL1) and possibly two file labels (HDR1 and HDR2 of a dummy file) at the logical start of the volume. The logical start of the volume is the position from which BS2000 can begin writing data. This is not necessarily the physical start of the volume.
In the case of magnetic tape cartridges, labels are never compressed when written, even if write access with compression has been specified (volume type TAPE-C4). The volume label (VOL1) is always written unencrypted, even when encrypted write mode is specified.

Up to 16 volumes can be initialized with one statement.

With all INIT or LIST functions, you can select a defined device that supports the corresponding volume type.

In order to prevent data being overwritten by mistake, each volume is checked for existing labels before new labels are created. The contents of existing labels are output to SYSOUT for scrutiny by the user. This means that the user has an opportunity to abort initialization.The read-before-write check is only not performed on magnetic tapes when the device management has already recognized the volume as empty and the INIT operand NEW has been specified.

If a volume is checked and a VOL1, HDR1 or HDR3 label is found to contain an access restriction (access pointer, release date, read or write password, “read-only” flag), a message to this effect is output.

The functions “read labels” (LIST statement) and “write new labels or tape marks” (INIT statement) are not executed unless the user has the “TAPE-ADMINISTRATION” privilege.

The INIT utility routine offers the following functions:

1. For magnetic tapes:

   • Write the volume header label VOL1 and the file header labels HDR1 and HDR2 (followed by two tape marks).

     Contents of tape: VOL1-HDR1-HDR2-TM-TM

   • Write only the volume header label VOL1 (followed by two tape marks).

     Contents of tape: VOL1-TM-TM

   • Write two tape marks at the logical beginning of the volume. No labels are written.

     Contents of tape: TM-TM

   • Dump the contents of VOL1, HDR1, HDR2 and HDR3 labels, if any, to SYSOUT or the console. New labels are not written.

   • Format the magnetic tape, if allowed by the volume and the tape device.

2. General:

   • Activating or deactivating special functions. The setting remains valid for all INIT and LIST statements for the duration of the program session or until reset.

   • Output an outline description of statements and operands.

   • Switch input/output to the console after the program is started with an ENTER task.

3. Security functions:

   • Specifies a check volume serial number. A magnetic tape is not processed unless the VSN in its VOL1 label tallies with the check VSN.

   • Erase the entire contents of the volume before writing new labels (DSE = Data Security Erase).

     In this context, erasure means that the volume is overwritten with a devicedependent deletion pattern. Several newer devices implement deletion only on a logical level by deleting the file management information on the volume. It may nevertheless still be possible to recover the information of earlier records using special devices and technically complex procedures. The only way to be absolutely certain that no unauthorized user reads any residual information left on the volume is to physically destroy the volume.

   • Abort initialization if a read-before-write check finds an access restriction.

   • Exclude special characters not defined in DIN 66003 from use in labels.