What is the identification number for a stacker's safety marking?

The correct identification number for a stacker's safety marking is the manufacturer code. This code is typically assigned by the manufacturer and is used to identify and distinguish the equipment. It contains crucial information about the stacker, which can include details about safety features, specifications, and the date of manufacture. The manufacturer code serves as a point of reference for safety compliance and helps with tracking any recalls or service requirements related to safety issues.

Other options like the serial number, model number, and registration code provide useful information for specific purposes but do not primarily serve the function of indicating safety features. The serial number is unique to each unit but is mainly for identification rather than safety. The model number identifies the specific model of the machine, and the registration code is often utilized for paperwork or regulatory requirements but does not directly pertain to safety markings as effectively as the manufacturer code does.