   module ietf-te-topology {
     yang-version 1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-te-topology";
     // replace with IANA namespace when assigned

     prefix "tet";

     import ietf-network-topology {
       prefix "nt";
     }

     container underlay-trail-src {
         uses nt:tp-ref;
         description
           "Source TE link of the underlay trail.";
       }
   }