It took me two days to figure this one out from my own PEB so I hope I have it figured out. I think the key is the translation of the V-codes on the unfit memorandum that a service member receives from the PEB that is sent to the VA requesting a rating. Yes or No indicate whether the injury falls under that specific deignation.
V1 = 10a
V3 = 10c
V4 = 10d
Once you have this little gem then you can find out what 10a, c, and d mean. Looking below, you will find that they are references to whether or not an injury is combat related.
This is what was on my unfit memo from the PEB. From what I can tell the V4-Yes next to the PTSD diagnosis indicates a combat type relationship.
o PTSD (MEB Dx 1) (V1-No; V3-No; V4-Yes)
o Lumbar DDD (MEB Dx 2) (V1-No; V3-No; V4-No)
o Right knee osteoarthritis (MEB Dx 3) (V1-No; V3-No; V4-No)
o Left knee osteoarthritis (MEB Dx 4) (V1-No; V3-No; V4-No)
o Chronic left lateral epicondylitis (MEB Dx 5) (V1-No; V3-No; V4-No)
All my PEBLO could tell me was that it has to do with taxes. It looks like these codes may also be used in determining eligibility for CRSC or CRDP but I am not sure on that. You will need someone smarter that I to answer that one.
Here is the link for the Google search results. The second result from the top is is to a Word document that is named "25 Jun 97". Don't fear this though, the document you will get to is the 24 Oct 2011 version. When I opened the link it asked for a login for hrc.army.mil but I hit cancel and the document opened up. It is a lengthy read but hopefully you will get a better idea what the codes mean.
"The above is a guide to be used in determining the proper designation of disabilities as combat related (10a, 10c, or 10d)."