I'm concerned about comments in the patch notes. Do I need to apply each PTF in the list or just RO97315? APAR: RO97315 CA OM WEB VIEWER PROBLEM 622 R11.5 SP00 LEVEL SET #4 PROBLEM CAUSE: Failure to apply the APARs in the correct sequence will require all of them to be re-applied. Apply all APARs in the order specified and verify the apply after each one.
There's no reason to be concerned. The Sustaining Engineers (SE) have made this one really easy for us. On some of the maintenance there would be a concern to make sure it goes on in in the specific, ascending order, but the level set PTFs are different. The boilerplate language, "Apply all APARs in the order specified and verify the apply after each one" really doesn't pertain in the case of the last Level Set APAR/PTF.
Level Set #4 is designed to go on to your 11.5 Web Viewer install regardless of it's current maintenance level. The only PREREQ is the base install (RO10102). So whether you just installed 11.5 Web Viewer out of the box, or the last PTF you put on was RO94802, as true cumulative maintenance, RO97315 should go on without problem (as long as you run ApplyPTF correctly).