.. _data.file.comments:

Comments
++++++++

These comments from an example SPEC data file scan:

.. code-block::
   :linenos:

   #C Fri Mar 11 16:29:51 2022.  plan_type = generator
   #C Fri Mar 11 16:29:51 2022.  uid = dccc572d-9a5b-4f72-87d7-233b2fd33e4e
   #C Fri Mar 11 16:29:57 2022.  num_events_baseline = 2
   #C Fri Mar 11 16:29:57 2022.  num_events_primary = 10
   #C Fri Mar 11 16:29:57 2022.  exit_status = success

are written to the :ref:`data.file.scan` entry as a single NeXus *field*
[#NX.field]_ named ``comments`` where all the scan's comments are joined together
by newline (``\n``) characters:

.. code-block::
   :linenos:

   comments:NX_CHAR = [b'Fri Mar 11 16:29:51 2022.  plan_type = generator\nFri Mar 11 16:29:51 2022.  uid = dccc572d-9a5b-4f72-87d7-233b2fd33e4e\nFri Mar 11 16:29:57 2022.  num_events_baseline = 2\nFri Mar 11 16:29:57 2022.  num_events_primary = 10\nFri Mar 11 16:29:57 2022.  exit_status = success']

Note, when printed, the value of this example ``comments`` field looks like::

   Fri Mar 11 16:29:51 2022.  plan_type = generator
   Fri Mar 11 16:29:51 2022.  uid = dccc572d-9a5b-4f72-87d7-233b2fd33e4e
   Fri Mar 11 16:29:57 2022.  num_events_baseline = 2
   Fri Mar 11 16:29:57 2022.  num_events_primary = 10
   Fri Mar 11 16:29:57 2022.  exit_status = success

.. [#NX.field] A NeXus **field** is the same as an HDF5 **dataset**.  The rename is   due to historical reasons in NeXus when XML was used as a back-end data file   storage format.