Basically "Other" is a broad category (e.g. able-bodied adults) that they can't put in the fixed categories.
I have no doubt that civilians are killed in these operations - civilians have always received the brunt in war, no matter how careful the armies are. (Something that has bothered me over the past few years is that "casualties" has come to mean "killed" when it used to mean "killed or injured".) There's little doubt that there are also many injured by these attacks that apparently don't show up in the reported numbers.
Micha Zenko at CFR has more - http://blogs.cfr.org...ed-by-u-s-drones/
:-(
Cheers,
Scott.