Mine is on my dogtags, but they currently reside on a mantle in my house, so they'd do me no good. I also served during the first gulf war, we wrote it on our helmet bands as well. Later, after 9/11, I was activated with the national guard, and we took to writing our personal info on our ribs. A few guys went so far as getting it tattoed there. How embarasing if it were the wrong blood type?