I don't think I've ever seen someone use M, NM, or nmi for nautical mile. I've only ever seen nm. I used nautical miles a lot in a previous career, in the conte

I don't think I've ever seen someone use M, NM, or nmi for nautical mile. I've only ever seen nm. I used nautical miles a lot in a previous career, in the context of aircraft mission planning. Telling people in the industry to use nmi or NM seems a lot like telling computer people to use MiB or GiB instead of MB or GB, or to pronounce gif "jiff". They're just not going to change.