Yeah, sure I got this, but this is not the issue. Let me explain my situation a bit more:
I have one media pool called "5 weeks" with retention set to 5 weeks.
Several tape jobs are targeted to this pool. One week backups takes about 8 tapes to store it.
After first week I put 8 tapes in offsite vault and put 8 scratch tapes in library. (this goes on and on)
After fifth week I have vault full of 40 tapes and I don't know, which tapes put into library, because I have no field that is saying, this tape is after its retention period and can be overwritten.
Or am I wrong?