From other discussions elsewhere, in order to qualify for this designation, it seems as if you have to have a significant disability that permanently disables you. Eg. It's not enough just to lose an arm and a leg, you have to be disabled in such a way that (current) prosthetics cannot restore your ability to work.

Of course, those are the standards/rules/regulations, but knowing the vast corruption within the US .gov, what actually happens is probably a different story.