30, 1979 processes all tape labels; CP does not process tape labels. tape label processing does not include: • Label processing for tapes that are read backwards • Processing of multivolume files on tapes • Support for ANSI tapes or ASCII labels • Label processing for any functions of the TAPE command except the
two functions DVOLl and WVOLl that' process VOLl labels USER RESPONSIBILITIES You must initiate all your own tape label processing. To specify that
you have a labelled tape, use the FILEDEF command for an OS simulaticn
program, or use a DOS DTFMT macro for a CMS/DOS program. You can also
use the TAPESL macro to process standard HDRl and EOFl lahels and the CMS TAPE command to write and display standard VOLl labels. You can
provide IBM standard label description details with the LABELDEF command for all types of label processing. After label processing has been
requested, it occurs automatically and there is no interaction between
you and CMS unless an error occurs. See the "Error Processing" secticn
later in this publication for a discussion of error processing • • LABEL PROCESSING IN OS SIMULATION If you are running an as simulation program and using OPEN and CLOSE macros, you specify the type of label processing you want in a FILEDEF command for a g1ven file. Detailed information about the FILEDEF
command is found in the You aay specify that you want standard label processing (with SL) or nonstandard
label processing (with NSL). If you choose nonstandard label
processing, you must already have written a routine to process
nonstandard labels. The name of this routine must be specified by the
filename in the NSL parameter on FILEDEF. An example of nonstandard
label processing is given in the section "NSL Processing". To be sure
that the tape you are using contains no IBM labels, you may specify no
label processing (NL) in the FILEDEF command. When NL is specified, ces does not open files on a tape containing a VOLl label as its first
record. You also can specify bypass tape label processing (BLP) on a
FILEDEF command. BLP tells CMS to bypass tape label processing for a
file, ana instead, to position the tape at a particular file before
processing the data records in the file. If you specify LABOFF for a
FILEDEF tape file, label processing is turned off and there is no tape
positioning or label checking. LABOFF is the default, so you do not receive any processing or tape
positioning for a tape file unless you specifically request it. If you
specify BLP, NL, SL, or SUL processing but omit a positional parameter,
the position defaults to 1 and the tape is positioned at the first file.
Examples of NL, BLP, and LABOFF processing are given in the sections "No Label (NL) processing", "Bypass Label (BLP) and "Label Off (LABOFF) processing".
122 IBM VM/370 CMS User's Guide

Pg. of GC20-1819-2 Rev March 30, 1979 by Supp. SD23-9024-1 for 5748-XX8 For IBM standard labels, you specify, SL or SUL, and optional positional
and VaLID parameters. On a FILEDEF command, SUL means standard user
labels. Everything you do for SL files, you must also do for SUL files.
The positional parameter for standard label files works the same way it
does in OS/VS. If you specify:
filedef filex tap1 sl 2
the tape is spaced to what is physically the fourth file on the tape
before processing begins. The reason for this spacing is that a
standard labelled tape has one header file, one data file, and one
trailer file for each data file. If you leave off the positional
parameter:
filedef filey tap3 suI you get the first file on the tape.
The optional VaLID parameter on the FILEDEF command allows you to
specify the volume serial number in the VOL1 label of a tape in case you
want only the VOL1 label checked on the tape. If you want to specify
other fields in IBM standard labels, you must also provide a LABELDEF
statement for the tape file. The LABELDEF statement allows you to
assign values to all fields in a standard HtR1 or EOF1 label. A
complete description of how the LABELDEF command works may be found in
the "LABELDEF Command" section later in this publication.
The following command defines filez as a standard labelled tane file
on a tape with a VOL1 label and a volume serial number of DEPT78: filedef filez tap1 51 volid dept78
If you also wish to specify a data set identifier for filez, you must
furnish a LABELDEF command for filez as well as the FILEDEF command.
Data set name may not be specified on the FILEDEF command. The LABELDEF
statement belcw assigns a data set name of payroll to filez.
labeldef filez fid payroll You can also specify file sequence number, volume sequence number,
expiration date and other fields on a LABELDEF command. However, if yeu
are using as simulation macros (OPEN, CLOSE, READ, GET, PUT, etc.) to process your tape file, the only LAEELDEF parameter that has
meaning for input files is fid (data set identifier). This is the only
field that is checked on input by as simulation. The other LABELDEF
fields are used to specify values to be written in output labels. They
are also used by other types of tape label processing (CMS/DOS and CMS) to check input labels. If no LABELDEF command has been supplied for
output files, default values are used to write out labels (see the
section on the LABELDEF command for the default values) • After you have set up your descriptive information for a standard
labelled tape file in FILEDEF and LABELDEF statements, you run a regular
as simulation program under CMS. During execution, HDR1 and
HDR2 labels are written or checked at OPEN time. EOF1 and EOF2 labels
are written or checked at CLOSE time. To have EOP labels processed, you
must issue a CLOSE macro. The VOL1 label on a tape is checked whenever
a file on that tape is opened if the user has specified a VOLID parameter on his FILEDEF statement or LABELDEF statement for the file.
If the ¥olid is specified on both LABELDEF and FILEDEF, the more recent
specification is used. If no valid is specified, it is not checked.
After checking the vOlid, the tape is positioned and the HDR label is Section 7. Using Real Printers, Punches, Readers, and Tapes 122.1