This document defines an ILS/MLS/GLS multi-mode receiver that provides the flight path deviation guidance to the aircraft during the final approach and landing phase. The data sources may be Instrument Landing System (ILS), Microwave Landing System (MLS) or GNSS Landing System (GLS). Supplement 4 adds ILS look-alike data (ARINC 429) in support of GLS CAT II/III operation. It also defines Final Approach Segment Data Messages (FASDM) input labels to the MMR for new aircraft.