[Zope] repozo, pack and backups

Hi, I'm hoping someone can share their experience of using repozo, packing and backups to answer a couple of questions. I've googled around to confirm that packing means a full backup. Is there any way to carry out incremental backups and then pack the database, without carrying out a full backup each time - for example, can I continue to get nightly incremental backups if I pack nightly but retain the last 2 days' transaction history? (I transfer the increments to a backup server, and then rebuild the database, then take a nightly snapshot to tape, so I really don't need a full backup) I have an inkling this is not possible, but would be useful to confirm... TIA, Miles