==== reference_descriptor

Defined by ARIB in <<ARIB-B10J>>.

[source,xml]
----
<reference_descriptor
    information_provider_id="uint16, required"
    event_relation_id="uint16, required">

  <!-- One per reference -->
  <reference
      reference_node_id="uint16, required"
      reference_number="uint8, required"
      last_reference_number="uint8, required"/>

</reference_descriptor>
----
