> With straight keys, side-swipers, and, to an extent, bugs, each and every telegrapher has their own unique style or rhythm pattern when transmitting a message. An operator's style is known as their "fist".

> Since every fist is unique, other telegraphers can usually identify the individual telegrapher transmitting a particular message. This had a huge significance during the first and second World Wars, since the on-board telegrapher's "fist" could be used to track individual ships and submarines, and for traffic analysis.

Ham = amateur radio operator: https://en.wikipedia.org/wiki/Amateur_radio