Learn the details of IBM® standard data set label 1 (HDR1/EOV1/TRL1) by reading this information. The IBM standard data set label 1 (HDR1/EOV1/TRL1) is 80 characters in length, and you use it to identify each data set.
| Offset | Data Type | Length | Contents |
|---|---|---|---|
| 0 | Character | 3 | Label identifier |
| 3 | Character | 1 | Label number |
| 4 | Character | 17 | Data Set (File) Identifier |
| 21 | Character | 6 | Aggregate volume identifier |
| 27 | Character | 4 | Aggregate volume sequence number |
| 31 | Character | 4 | Data Set (File) sequence number |
| 35 | Character | 4 | Generation Number (not used) |
| 39 | Character | 2 | Generation Version Number (not used) |
| 41 | Character | 6 | Creation Date |
| 47 | Character | 6 | Expiration Date |
| 53 | Character | 1 | Data Set (File) Security (not used) |
| 54 | Character | 6 | Block Count, Low Order (Trailer labels only) |
| 60 | Character | 13 | System Code (Trailer labels only) |
| 73 | Character | 3 | Reserved |
| 76 | Character | 4 | Block Count, High Order (Trailer labels only) |
The program records the data set label in EBCDIC.
The program describes the contents and function of each of the following fields.
The characters identify the type of data set label.
The relative position of this label, within a set of labels of the same type; it is always 1 for the IBM data set label 1.
A unique identification code to identify the data set (file). If the data set ID is less than 17 characters, it is left-aligned, and you pad it with blanks.
This field contains the volume identifier from the volume labels of the first volume in a multivolume data set.
This field contains the relative volume number of this volume in a multivolume data set. The field is 0001 for a single volume data set.
This field indicates the relative position of the data set within a multiple data set group. The value will be in EBCDIC displayable characters for 0001–9999. For numbers larger than 9999 that will not fit in the 4–character field as an EBCDIC displayable character set, the first byte will a '?' ('6F'x) for EBCDIC labels. The last three bytes will be a binary number from 1 to 64000.
If the data set is a part of a generation data group, this field contains a number that indicates absolute generation number. i5/OS™ does not use this field.
If the data set is part of a generation data group, this field contains a number that indicates the version number of the generation. i5/OS does not use this field.
The creation date of the data set. The program shows the date in the format cyyddd, where:
c = century (blank=19; 0=20; 1=21; and so on)
yy = year (00-99)
ddd = day of the current year (001-366)
Note that the century code gives the first two digits of the year, not the actual century. For example, a blank which translates into 19 indicates a year in the 1900s, not in the nineteenth century.
The date the program considers the data set expired. Expiration date refers to a data set that is allowed to be overwritten. The user specifies the date in the open tape file that is used in writing the tape. You ignore the expiration date on input, and verify the expiration date on output by i5/OS. The date is in the format cyyddd, where:
c = century (blank=19; 0=20; 1=21; and so on)
yy = year (00-99)
ddd = day of the current year (001-366)
Note that the century code gives the first two digits of the year, not the actual century. For example, a blank which translates into 19 indicates a year in the 1900s, not in the nineteenth century.
The field in the trailer labels contains the low order six digits of the number of data blocks in the data set on the current volume. The field in the header labels contains hex zeros.
The field in the trailer labels contains the high order four digits of the number of data blocks in the data set on the current volume. The field in the header labels contains hex zeros.