Thank you, Alessandra,
already resolved the problem, which turned out to be not in cleaning but in sending to TM. In the 'Send Project to TM' menu I did finally notice 'MT segments' flag, exactly what I wanted.
Your comments about SQL were interesting, I'll try to apply them to the extent my abilities allow.
--- In firstname.lastname@example.org, Alessandra Muzzi <mail@...> wrote:
> Here are a few handy SQL statements for MDB maintenance. Run them at
> your own risk! Better use a copy of your databases, or backup them first.