They would either be part of the sequence (so their ID would be the same as ``SequenceID``), part of the ``SequenceID`` (in which case we'd probably just want their ID to be the same as ``SequenceID``), or in their own file, in which case there is nothing different about them than any other fastq file, so both the sequence and the id should end up in ``SequenceID`` and ``Sequence``. I think ``BarcodeID`` probably isn't necessary.