grazie42:Like others have said, how hard would it be to forge a logbook?!
Now I'm not a DM or run any diveops but...
It's not hard to write down a bunch of crap into paper thingy (yes, that's the technical name) but while you still can manually input dives into SDM or something, its a pretty complicated process and not worth the trouble, especially if they display the readouts of every 10 seconds of a fifty minute dive. Thus I'd think that unsigned Dive Manager printouts would be considered legit. But again, I'm not someone who is responsible for checking someone's dive credentials (except my buddy).
-Pols