LS3a oxygen cylinder specification

I am trying to get my oxygen cylinder inspected for refilling. It is due
for a hydro test and inspection. However there has been a shake up of
cylinder inspections in the local dive industry and as a result the
inspector is checking all the paperwork very thoroughly. Unfortunately
he cannot identify the manufacture specification from the markings on
the cylinder, which is a bit of an issue.

The cylinder was supplied by Rolladen Schneider, with my LS3a, when it
was delivered new. It is a steel 4l cylinder, manufactured in Germany in
1979 that fits exactly into the molded O2 cylinder recess in the glider.
Does anybody know what the applicable manufacturing specification would
been at that time?

Thanks

Ian