This reports the FDDI port type of this specific port - an A port and B port on a dual-attached station, an S port on a single-attached station, an M port on a concentrator's master port, or unknown. Administrators use it to understand this port's role in the FDDI ring topology, which affects how it's expected to be cabled and how the ring should be diagnosed if there's a fault. A value of m tells an admin this port is a concentrator master port used to connect single-attached stations into the ring, rather than being part of a dual ring itself.