ISO/ANSI standard data set label 1 (HDR1/EOV1/EOF1)

 

The ISO/ANSI standard data set label 1 (HDR1/EOV1/TRL1) is 80 characters in length and is used to identify each data set. The system records the data set label in ASCII.

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

Offset	Data type	Length	Contents	File Type
0		3	Label identifier
3		1	Label number
4	Character	17	File Identifier
21	Character	6	File Set Identifier
27	Character	4	File Section Number
31	Character	4	File Sequence Number
35	Character	4	Generation Number (not used)
39	Character	2	Version Number (not used)
41	Character	6	Creation Date
47	Character	6	Expiration Date
53	Character	1	Accessibility
54	Character	6	Block Count, Low Order (Trailer labels only)
60	Character	13	System Code (Trailer labels only)
73	Character	7	Reserved

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The manual 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 the set of labels of the same type; it is always 1 for the data set label 1.

• File Identifier

  A unique identification code to identify the data set (file). If the data set ID is less than 17 characters, it is left justified and padded with blanks.

• File Set Identifier

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

• File Section 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.

• 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 (not used)

  If the data set is a part of a generation data group, this field contains a number that indicates an absolute generation number. i5/OS^® does not use this field.

• Version Number (not used)

  If the data set is part of a generation data group, this field contains a number indicating 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 program considers the date in which the data set expires. Expired refers to a data set being allowed to be overwritten. The user specifies the date in the open tape file used in writing the tape. The i5/OS ignores the expiration date on input, and verifies the expiration date on output. 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.

• Accessibility A code number indicating the security status of the data set. i5/OS does not use this field. The following values indicate data set security values created by other systems:

  blank

  No data set access protection

  1

  Password protection (Required for read/write/deletion)

  3

  Password protection (Required for write/deletion)

  other character

  Protected volume, no access possible

• Block Count (Trailer labels only)

  The field in the trailer labels contains 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

 

Parent topic:

Volume label fields