The entity hierarchy of the HDLC module is:

    Node___HDLC____Link____Logical_Station
                 |
                 |_Port

    The HDLC entity is the top-level entity in the hierarchy of
    entities belonging to the HDLC module.

    An HDLC LINK entity is associated with a port of the supporting
    physical layer module. It contains attributes common to local
    HDLC operations for all logical stations on the line. The link-
    name refers to the HDLC link managed by this command.

    The HDLC LINK LOGICAL STATION entity controls the characteristics
    of an HDLC logical station. There is one station for each remote
    termination of a line associated with the HDLC link. The link-
    name is the link entity within the HDLC module and the logical-
    station-name refers to the logical station managed by this
    command.

    The HDLC PORT entity represents one end of an HDLC connection.
    The entity maintains information about that link. Ports are
    created and deleted automatically when a client of HDLC uses the
    link. The port-name refers to the port managed by this command.