==== data_content_descriptor

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

[source,xml]
----
<data_content_descriptor
    data_component_id="uint16, required"
    entry_component="uint8, required"
    ISO_639_language_code="char3, required"
    text="string, required">

  <selector_bytes>
    Hexadecimal content
  </selector_bytes>

  <!-- One per component_ref -->
  <component ref="uint8, required"/>

</data_content_descriptor>
----
