==== vvc_subpictures_descriptor

Defined by DVB in <<ETSI-300-468>>.

[source,xml]
----
<vvc_subpictures_descriptor
  default_service_mode="bool, required"
  processing_mode="uint3, required"
  service_description="string, optional">
  <subpicture
    component_tag="uint8, required"
    subpicture_id="uint8, required"/>
</vvc_subpictures_descriptor>
----
