Telco 20260318

Date

Wednesday, 18th Mar, 15:00 UTC

Connect

Agenda

  • NeXus paper

  • NIAC 2026

  • NeXus Ontology

  • NXxas

Present

SB, AB, FS, PC, FdA - MarkusK (FAIRmat), MariusR (ESRF)

Minutes

  • feedback on the paper

    • MK: affiliations need to be finalized; new revision is prepared; constructive feedbacks received; next step is finalisation

    • AB: the NeXus submission to IUCR has a shortened notation for describing examples; Sci Data, Nat Prot, or Nat Methods can be alternatives for target

  • NIAC 2026

    • FdA: format is extended satellite also over the week-end organised at DESY

    • AB: NIAC Meeting is an important vehicle of NeXus community. 3 days with 3 sessions in hybrid (10:00, 13:30, 16:00), but also open sessions (10:00 and 13:30) with call for abstracts (2 session x3 talks, 20 mins each) for Friday (Sep 25)

  • NeXus Ontology

    • SB: PAN has been registered in w3id. PR for registering PAN/NeXus is ready. After the IRI namespace is registered, NeXus Ontology itslef can also be updated. We have agreed that Heike can be the official contact person at w3id. It has turned out that we can list more contact persons.

    • AB: we should also list the NeXus Executive Chair (Aaron for the moment). At the NIAC meeting, we will also be able to create an official role for a NeXus Ontology Officer

  • new proposal for NXxas

    • MR: proposal history and latest PR were presented. Alternatives: (A) inherited Application Definitions. (B) NXxas with optional base classes for respective measurement modes. Note that (B) assumes that instruments/detectors would be part of these measurement mode base classes, and would not follow the generic NeXus hierarchies.

    • MK: going like this, the base class will not be reusable in any other field/use case.

    • SB: Note that base classes do not contain restrictions (e.g. required fields). They all have to be listed in the Application Definition.

    • MK: Note that NXatom is already part of NeXus. NXelement lists the full periodic table, but it might not be necessary, but rather connect to other namespaces (ontologies)

    • MR: (B) seems to be more problematic. NXelement is reusable and can have its place in NeXus as a base class (although it may need to be connected to other ontologies at one point in future). NXelement could extend NXatom. Shall we do 2 separate PRs for easier review?

    • PC: Yes, it is working

    • SB: Both base classes and Application Definitions can be put to Contributed after a quick review. When the community has already started to use and is happy with the definirinos, they can be voted on and brought to the standard.

    • MR: NXemission_lines is only for grouping emission lines. LP has referred back to discussion on NXbag.

    • MK: Still do not understand why a group cannot inherit directly from NXobject, but needs to inherit from another base class.

    • SB: we may want to visit this question again, because NXobject is now a properly defined base class

    • MR: can we use an Application Definitinos for a group

    • SB: currently AppDefs can be used only inside NXentry and NXsubentry. Inside a definition it can only be used via inheritance when a new Apdef is defined using ‘extend’ and not when a new group is defined via specifying its ‘type’.

    • MR: ‘choice’ did not render properly, but can be fixed as in PR #1613

    • PC: yes, this fix is needed

    • MR: we bring the new definitions to XAFS 2026 (June 21-26, in Thailand)

    • SB: a mofied EWOKS workflow from ESRF’s ID21 can be a good demonstrator for its use

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