Question: What is the difference between Generation number and version number in GDG
Answer: The V originally stood for volume and was used to allow the individual tapes within a multi-tape generation to be individually referenced.
When used with single volume storage the highest volume number specified willbe the only version of the particular generation that is accessible via the GDG.
Say that you have the following files:
mygdg(0) references g0003v00
mygdg(-1) references g0002v01
mygdg without qualification will grab g0001v00, g0002v01 and g0003v00
With v01 specified the v00 becomes inaccessible unless directly accessed by name.
This article written by Stephen Chapman, Felgall Pty Ltd.