Applies only to nodes on broadcast circuits.  Specifies the physical
 address that the target node currently use to identify itself.
 The value is the physical address the target node has set for
 itself, or, if the target node has not set a physical address, the
 HARDWARE ADDRESS parameter if associated with the target node in the
 executor node's volatile database.  This parameter must be included if
 a broadcast circuit is specified in VIA circuit-id.