How does Versions work with iCloud?

Just wondering how, if at all, Versions on Pages for Mountain Lion (10.8) works with iCloud, specifically in relation to iOS 5 devices. My own testing seems to indicate that a Pages document created on the Mac saves versions in iCloud that you can revert to but only on the Mac (can't find an iOS interface for Versions). However, if I create a document on Pages for iOS (forcing an upload to iCloud after each edit) I can't revert to previous versions made on iOS, even on the Mac. One time, when I tried to do this, I saw a message saying the file is stored on a volume which doesn't support permanent version storage. However I have been unable to reproduce this message. Can anyone enlighten me as to how Versions is supposed to work with iCloud? Is it a Mac-only feature, not available on iOS? If so, how best to guard against unwanted edits on iOS? Should I just prevent the doc from being uploaded to the cloud until I am happy with it, and use the undo / redo feature? As I understand it, we only have Versions on the Mac because we also have Autosave. On iOS all saving (to the cloud) is done manually (the equivalent of the old command-s on Snow Leopard) thus eliminating the need for iOS versions. Have I got the correct picture here? Sorry for the long post! I'd really appreciate any replies.