This European Standard specifies general minimum frame requirements for units designed to switch and/or monitor individual or groups of lamps in an Aeronautical Ground Lighting (AGL) series circuit, regardless of the switching or monitoring technology used. It applies to units connected directly to either the primary or secondary side of an AGL circuit for selective lamp control and monitoring. The standard does not address communication protocols, application procedures, or system aspects affecting AGL operation. Note: These units can be used as part of either a Surface Movement Guidance and Control System (SMGCS) or an Advanced Surface Movement Guidance and Control System (A-SMGCS) to guide or control aircraft surface movement using visual aids.