First: thanks for all the people who answered my previous questions.
Very much appreciated.

I'm stuck (i.e. regardless of whether this makes sense, or no, sounds familiar?)
with the following set of requirements:

* 5 machines (it's good: 5 days/week, one overnight run/machine)
* one full backup of all machines/month
* four incremental backups/month, relative to above full dumps
* two months sliding window, after which incremental backup tapes are reused
* storage depth of one year

So I'm going to use a tape/day, labeled DailyMachineWeekdayNumber,
e.g. u03Monday01,u03Monday02, u03Monday03, u03Monday04. Is it possible to 
promote
a full dump, say, Monday for u01, Tuesday for u02, etc., and store diffs 
relative
to it?

How do I do that?

TIA,

Eugen Leitl