Apparatus and method for marking a J-line

A marking unit comprising:

• a writing device that marks a material web, said material web windable onto a core by means of a winding device to form a reel,
• wherein the marking unit has a signal generator that is operatively connected to the core of the winding device, said signal generator outputting a clock signal to the writing device that marks the material web, wherein the marking unit has a plurality of writing devices, the writing devices arranged at different positions, wherein the clock signal for the respective markings of the material web is output simultaneously to the plurality of writing devices.

A method for marking a material web which is wound up onto a core by means of a winding device to form a reel, comprising the steps of:

• outputting a clock signal to a writing device utilizing a signal generator operatively connected to the core of the winding device, said clock signal based on rotation of the core, the clock signal being output to the writing device by the signal generator upon each completed revolution of the core;
• and
• placing a mark on the material web utilizing the writing device on the basis of the received clock signal.