I'm purchasing a brick on a memorial for my grandfather, and I have a limitation on the characters I can use.  He served as a USN Aviator from 1942 through 1966 and served in WWII, Korea and Vietnam.

The limitation is such that I need to abbreviate the last line:  1942-1966 WWII, KR, VN

Is that the correct way to do it, or should it have "KOR" instead of "KR"?  I have 23 characters for that line (including spaces).

You have the extra space.  I would go with KOR.

You could use KOR, but the country we were defending was the Republic of Korea, ROK. You could also use RVN for Republic of Vietnam.

I have seen "KOR" and "VN" on headstones and such, but I don't know if that is a funerary custom, or just a pragmatic thing. They aren't the proper names politically, but I realize that's not the point, although I think it is more consistent also with what our troops used to call theirs: ROKs ("rocks") and ARVNs ("Arvins").

ETA: "1942-66: WWII, ROK, RVN" is 23 characters with spaces.

ETA2: Arlington undoubtedly has written standards about every conceivable thing, but since this is a brick and not a national cemetery, maybe it's not worth the worry.

I appreciate the replies.  I had "KOR" which seemed the most intuitive to me - but I wanted to make sure that it wasn't improper.  "KO" or "ROK" seems to be the most 'correct' way to do it.  However, I would prefer "KOR" as long as it's not some faux pas or where someone who was a war vet would look at that and scoff.

I have 23 spaces per line, so I have:

[his name]
LCDR US NAVY, Air Medal
1942-1966 WWII, KOR, VN

His headstone in Arlington has them all completely written out on separate lines, but I don't have the space for that:

WORLD WAR II
KOREA
VIETNAM

Thank you!