Detector channels

[phyy-nx]

This PR adds NXdetector_channel as a base class and adds it as optional for NXmx. @soph-dec and @kalcutter I put in placeholder documentation. Can you review and comment?

See original Dectris proposal: https://github.com/dectris/documentation/tree/main/filewriter_v2#user-content-multi-channel-data

Closes #940 Requires #1246 to be merged first

Co-authored-by: Sophie Hotz sophie.hotz@dectris.com

[soph-dec]

Thank you for the PR Aaron! First glance is looking good, I will review everything in detail next week.

[phyy-nx]

I think we should mention NXdetector_channel in NXdetector as well. I guess something like this might do?

  <group name="CHANNELNAME_channel" type="NXdetector_channel">
      <doc>
          Group containing the description and metadata for a single channel from a multi-channel
          detector.

          Given an :ref:`NXdata` group linked as part of an NXdetector group that has an axis with
          named channels (see the example in :ref:`NXdata &lt;/NXdata@default_slice-attribute&gt;`),
          the NXdetector will have a series of NXdetector_channel groups, one for each channel,
          named CHANNELNAME_channel.
      </doc>
  </group>

Done! Also added to NXmx

[phyy-nx]

Conflicts fixed, no changes to this branch.

Reviewers might find it easier to use this link to compare the detector_channel branch to the dimension_as_char branch until #1246 is merged: https://github.com/nexusformat/definitions/compare/dimension_as_char...detector_channel

[phyy-nx]

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[phyy-nx]

Vote has passed. Thanks all.