Abstract: Apparatus for applying characters to packages or other objects advanced through a marking station. The characters, which each consist of a pattern of points or spots, are applied by the discharge of ink onto the object from a plurality of nozzles arranged in a row extending transversally of the direction of advancement of the object. Each of the nozzles is connected through a solenoid valve to a source of pressurized ink. The solenoid valves are controlled by a pattern generator which at predetermined intervals selects solenoid valves to be activated and causes a simultaneous opening pulse to be supplied to the solenoid valves selected. The height of the characters can be varied by means of switch means whereby one or the other of two groups of solenoid valves, corresponding to two groups of nozzles in said row, is rendered available for the selection.