If a Bridge supports encoding or decoding of drop_eligible from the PCP field of a VLAN tag (6.7.3) on any of its Ports, then it shall implement a Boolean parameter Require Drop Encoding on each of its Ports with default value false(2). If Require Drop Encoding is True and the Bridge Port cannot encode particular priorities with drop_eligible, then frames queued with those priorities and drop_eligible true(1) shall be discarded and not transmitted.