When upgrading your ZMF systems, a summary of the changes you can expect to see may be found in the ‘New Features and Fixes’ section of the Readme file associated with that release. For example, this documentation for the ZMF 8.3 release may be found here. 
Also, as mentioned in the Readme files, if you are upgrading from anything other than the prior software level, e.g. if you are upgrading to ZMF 8.3 from anything other than 8.2 Patch 7, you must also refer to all new features and fixes implemented in those interim releases that have been skipped. Again by way of example, you can obtain a summary and/or links to the enhancements and fixes in all of the ChangeManZMF 8.2.x releases from the ZMF 8.2 Patch 7 Readme file, which may be accessed here.