In
telecommunication, a
n-entity is an active element in the
n-th layer of the
Open Systems Interconnection--Reference Model (OSI-RM) that (a) interacts directly with elements,
i.e., entities, of the layer immediately above or below the
n-th layer, (b) is defined by a unique set of rules,
i.e.,
syntax, and
information formats, including
data and control formats, and (c) performs a defined set of functions.