I do not have a formal checklist. I have to admit, in the past, we have typically ran into upgrades before we did CPS updates. Given that CPS updates change code and patch bugs, I would start by reading the release notes and what files are changing. There should be an extensive list of SPRs and other security issues address. If you have done and customization or modified any PTC files, you need to make sure that if any of those files have been updated, you take account and merge in changes.
Functionality should not have changed but if they were fixing a bug, there might be slight alterations. A full round of functionality testing would be advised to ensure that the CPS was applied correctly and there was no configuration issue. CPS updates can update Apache and related services so take note if that is occurring.
