module reference-in-unknown {
  namespace "urn:ref:unknown";
  prefix "riu";

  extension test-extension {
    argument test;
  }

  riu:test-extension {
    container cont {
      description
        "This is just a plain text";

      list mylist {
        description
          "This is a just another plain text";

        reference "refers somewhere...";

        leaf myleaf1 {
          type string;
        }

        leaf myleaf2 {
          type string;
        }
      }
    }
  }
}