Carolyn
Surely he could have gotten a couple of purple hearts in OCS if he had tried hard enough!
I don't know for sure, but I don't think so. It looks like there are two separate Service Data sections, both followed by VA data and authentication. The first applies to OCS and the second applies to Active Duty. The "Not Applicable" is part of the first Service Data section, so it does not look like it applies to Vietnam.
To look at it another way, when the officer signs off on the Authentication Section, all of the data above that line should be complete. The first Authentication, which is below Line 27, would have been completed before Kerry went to Vietnam.
Now, I have no specialized knowledge of Military forms, but that is my take. Maybe some of our military-experienced FReepers can offer a more authoritative opinion.