==== caption_service_descriptor

Defined by ATSC in <<ATSC-A65>>.

[source,xml]
----
<caption_service_descriptor>

  <!-- One per service -->
  <service language="char3, required"
           digital_cc="bool, required"
           line21_field="bool, optional"
           caption_service_number="uint6, required"
           easy_reader="bool, required"
           wide_aspect_ratio="bool, required"/>

</caption_service_descriptor>
----
