...
>Basically, he wants to know if there is any way that when the data expires it
>becomes completely unusable/unrecoverable, even by someone with the
>time/money/motivation to take a scratch tape and piece together what's on it.

By data processing definition, tapes - like disks or any other media (including
paper) - are supposed to be physically secure, as in kept in a room that
non-authorized people cannot enter, and that the people in the room are
trustworthy.  That is the fundamental protection for tapes written by any
application.

Expiration is a logical process, not physical: nothing goes near the tape in the
process.  Only the "catalog entry" for the expired data is obliterated, while
the tape remains intact.  Being an append-only medium, there is no potential for
partial erasure of tape contents.  You can wholly write over the tape with
binary zeroes when it is empty if you like, to obliterate prior contents; but
next use effects obliteration anyway.  Note that *SM tape data format is
unpublished: even we as *SM administrators don't know how to physically access
it.

I think your department manager needs to clarify exactly what he wants vs. the
standards and protections which prevail for tape data.

  Richard Sims, BU