IBM standard data set label 1 (HDR1/EOV1/EOF1)

 

The IBM^® standard data set label 1 (HDR1/EOV1/TRL1) is 80 characters in length, and you use it to identify each data set.

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Table 1. Format of the IBM Standard Data Set Label 1 (HDR1/EOV1/EOF1)

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)

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The program records the data set label in EBCDIC.

The program describes the contents and function of each of the following fields.

• Label identifier

  The characters identify the type of data set label.

  • HDR - Header Label (the beginning of a data set)

  • EOF - Trailer Label (the end of a data set)

  • EOV - Trailer Label (the end of a data set that is continued on another volume)

• Label number

  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.

• Data Set Identifier (file name)

  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.

• Aggregate volume identifier

  This field contains the volume identifier from the volume labels of the first volume in a multivolume data set.

• Aggregate volume sequence number

  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.

• Data Set (File) sequence number

  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.

• Generation Number that is not used

  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.

• Generation Version Number (not used)

  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.

• Creation Date

  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.

• Expiration Date

  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.

• Data Set (File) Security that is not used A code number indicates the security status of the data set. i5/OS does not use this field. The following values indicate data set security values that are created by other systems:

  0

  No password protection

  1

  Password protection (required for read/write/deletion)

  3

  Password protection that is required for write/deletion.

• Block Count, Low Order (Trailer labels only)

  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.

• System Code (Trailer labels only) A unique code that identifies the system that created the data set.

  IBMOS400

  IBM i5/OS (previously OS/400^®)

  IBM OS/VS 370

  IBM MVS™ operating system

• Block Count, High Order (Trailer labels only)

  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.

 

Parent topic:

Volume label fields