HP uses the designation for a specific line of LaserJet printers .

In cryptic posting, using G-code references can imply a "loading" or "paused" state, as the M109 command literally halts all other operations until a certain condition (heat) is met. 2. Military Technology (M109 Howitzer)

In the world of 3D printing, is a standard G-code command used to set the hotend temperature and wait for it to be reached before continuing the print.