An anecdote: I used to work at a US company where, out of laziness, people referred to the millimeter as a "mil." I was sure confused at first, since I was familiar with mil in the inches sense. For example, when somebody said he wanted to use a 6 mil screw, I'd reel in shock for a second before realizing that he meant a 6 millimeter screw ('cause who ever heard of a screw 0.006" in diameter?).