ABCs of z/OS System Programming Volume 3 - IBM Redbooks

4.20 Absolute generation and version numbers
A.B.C.G0001V00
A.B.C.G0009V01
Figure 4-30 Absolute generation and version numbers
Generation Data Set 1, Version 0,
in generation data group A.B.C
Generation Data Set 9, Version 1,
in generation data group A.B.C
Absolute generation and version numbers
An absolute generation and version number is used to identify a specific generation of a
GDG. The same GDS may have different versions, which are maintained by your installation.
The version number allows you to perform normal data set operations without disrupting the
management of the generation data group. For example, if you want to update the second
generation in a three-generation group, then replace generation 2, version 0, with
generation 2, version 1. Only one version is kept for each generation.
The generation and version number are in the form GxxxxVyy, where xxxx is an unsigned
four-digit decimal generation number (0001 through 9999) and yy is an unsigned two-digit
decimal version number (00 through 99). For example:
► A.B.C.G0001V00 is generation data set 1, version 0, in generation data group A.B.C.
► A.B.C.G0009V01 is generation data set 9, version 1, in generation data group A.B.C.
The number of generations and versions is limited by the number of digits in the absolute
generation name; that is, there can be 9,999 generations. Each generation can have 100
versions. The system automatically maintains the generation number.
You can catalog a generation using either absolute or relative numbers. When a generation is
cataloged, a generation and version number is placed as a low-level entry in the generation
data group. To catalog a version number other than V00, you must use an absolute
generation and version number.
Chapter 4. Storage management software 141