Physical signaling sublayer

Physical signaling sublayer (PLS): In a local area network (LAN) or a metropolitan area network (MAN) using open systems interconnection (OSI) architecture, the portion of the physical layer that (a) interfaces with the medium access control sublayer[?], (b) performs character encoding, transmission, reception, and decoding, and (c) performs optional isolation functions.

Source: from Federal Standard 1037C