==== HEVC_tile_substream_descriptor

Defined by MPEG in <<ISO-13818-1>>.

Either one single `Reference` element or multiple `Substream` elements can be present (or none).

[source,xml]
----
<HEVC_tile_substream_descriptor
    SubstreamID="uint7, required">

  <Reference
      PreambleFlag="uint1, required"
      PatternReference="uint7, required"/>

  <Substream
      Flag="uint1, required"
      AdditionalSubstreamID="uint7, required"/>

</HEVC_tile_substream_descriptor>
----
