==== supplementary_audio_descriptor

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

[source,xml]
----
<supplementary_audio_descriptor
    mix_type="uint1, required"
    editorial_classification="uint5, required"
    language_code="char3, optional">
  <private_data>
    Hexadecimal content
  </private_data>
</supplementary_audio_descriptor>
----
