I agree with you on the diversity of versions of ZIP out there. I'd say most of the differences would be in its encryption algorithm. (I am not in the US, so I am using the export version of the strong encryption algorithm to compile my ZIP program, hmmm, perhaps that is why I still haven't had any problems yet.) Provided there is no encryption requirement, ZIP is still a good solution though. And of cause if there was any problem, it would show up in the testing phase, wouldn't it?