Editing EPrints Package Manager (section)

===Installing & Upgrading===
These are essentially the same as the EPM Manager will check each file it is attempting to installed to see if it meets the following conditions.

====Before install/upgrade====
* Make a backup of any previously installed version of this package.

====During install/upgrade====
* If no file exists at destination install from EPM package, record the installed checksum.
* If a file exists and is managed by a previous version of this package (by checksum) copy the new one over the top and checksum.
* If a file exists and is not managed by a previous version of this package (including if it has been changed since the last install), abort and remove files installed to this point, then put back the old files. 

====After successful install/upgrade====
* Attempt to reload the repository, if this fails, abort and rollback as the user may loose the ability to launch the package manager to do this later!
* Store checksums, spec file and related package files (e.g. package icon) locally overwriting any previous.