Proposal 1. Introduce the "isReference" parameter to signify that a given Network Object is defined elsewhere and 
augmented here.

Discussion: it is yet unclear if "elsewhere" means "elsewhere in this document", "elsewhere in another document", "
defined by another organisation" or some of these.

Proposal 2: Use the following syntax:

XML:

<nml:Link id="urn:ogf:network:example.net:2012:mylink-a-to-b">
  <nml:property name="isReference">true</nml:name>
</nml:Link>

which is equivalent to:

<nml:Link idRef="urn:ogf:network:example.net:2012:mylink-a-to-b" />

RDF:

 urn:ogf:network:example.net:2012:mylink-a-to-b   nmlprop:isReference   "true" .