Data mile
Template:Infobox unit In radar-related subjects and in JTIDS, a data mile is a unit of distance equal to Template:Convert. An international mile is 0.88 data mile.
The speed of light is Template:Convert, or about one foot per nanosecond. If it were exactly one foot per nanosecond, and a target was one data mile away, then the radar return from that target would arrive 12 microseconds after the transmission. (Recall that radar was developed during World War II in America and England, while both were using English units. It was convenient for them to relate 1 data mile to 12 microseconds, whereas the modern tendency would be to approximate the speed of light as 300,000 km/s.)