Can someone explain to me which of the following two segments are correct? <nml:BidirectionalPort id="urn:ogf:network:netherlight.net:2013:port:a-gole:testbed:232"> <nml:PortGroup id="urn:ogf:network:netherlight.net:2013:port:a-gole:testbed:232:in"/> <nml:PortGroup id="urn:ogf:network:netherlight.net:2013:port:a-gole:testbed:232:out"/> </nml:BidirectionalPort> or <nml:BidirectionalPort id="urn:ogf:network:ampath.net:2013:ndn"> <nml:name>ndn</nml:name> <nml:Port id="urn:ogf:network:ampath.net:2013:ndn-in"/> <nml:Port id="urn:ogf:network:ampath.net:2013:ndn-out"/> </nml:BidirectionalPort> Should Port or PortGroup be used? We have a mix right now in our topologies. Thanks, John