From my own account and from the Admin account, I have the ability to not only 'Get Latest Version' (from the 'Action' menu) but I also have another option 'Get Version' which allows me to get previous versions.  My CAD user clients do not see this option in their Action menus.

I've experimented a bit, but I can't figure out which permission grants users the option to get earlier versions in this way.  Is there an easy ON/OFF permission for this function?