I have revived someone when they didnt want it. I knew there were enemy soldiers in sight. I couldnt take them all. I revived to get help, but then realized that i was not helping anything. You die and learn. lol I know now not to revive unless we are behind protective cover or out of the sight of enemy infintry. A "DNR" option would be nice to have though. Sometimes i dont want to be revived in order to switch to a different class, to help the squad for the situation at hand.