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