puts the db into recovery mode so that nothing can modify it, but it's ready to accept restorations.
this backup vendor... you can take an ad-hoc transaction log backup but you can't do it with norecovery. what does this mean? two things:
first: in order to put the db into recovery mode, you have to do a COMPLETE restore and "keep database in restoring state" -- this is RIDICULOUS and wasteful when all that needs to happen is a tiny tlog backup with norecovery.