NXsas: review use of minOccurs on various components

[prjemian]

For base classes, minOccurs=0 is the default and means the dataset is optional. For application definitions, the default is minOccurs=1 which means it is required. (HDF5 imposes maxOccurs=1 since item names must be unique within a group).

add: NXsas documentation

[prjemian]

important to make next milestone

[prjemian]

Do this with a branch+PR

[zjttoefs]

NXsas has no instances of max* or minOccurs. What is there to review? Is this a proposal to change the application definition?

[prjemian]

The application definition should be examined to determine which components must be given or that some components need a declaration of minOccurs=0. For example, must NXsample always be provided? Must the NXdata group only be named data?

[benajamin]

@prjemian is this (and NIAC#58) still relevant?

[prjemian]

@benajamin : Yes, and Yes.

@zjttoefs You asked above:

NXsas has no instances of max* or minOccurs. What is there to review? Is this a proposal to change the application definition?

We should review the definition with this question:

• Is the NXsas definition missing these attributes (max* or minOccurs)?

If they are missing (it is likely the existing application did not consider these attributes) and the need for them sufficient, we should propose changes to NXsas in a branch.

[prjemian]

This is the structure of the NXsas definition at this time. None of the items are marked optional or minOccurs=0:

NXsas (application definition)
  (overlays NXentry)
  NXentry
    @entry
    definition:NX_CHAR
    end_time:NX_DATE_TIME
    start_time:NX_DATE_TIME
    title:NX_CHAR
    data:NXdata
      data --> /NXentry/NXinstrument/NXdetector/data
    instrument:NXinstrument
      name:NX_CHAR
      collimator:NXcollimator
        geometry:NXgeometry
          shape:NXshape
            shape:NX_CHAR
            size:NX_FLOAT
      detector:NXdetector
        aequatorial_angle:NX_FLOAT
        azimuthal_angle:NX_FLOAT
        beam_center_x:NX_FLOAT
        beam_center_y:NX_FLOAT
        data:NX_NUMBER[nXPixel,nYPixel]
        distance:NX_FLOAT
        polar_angle:NX_FLOAT
        rotation_angle:NX_FLOAT
        x_pixel_size:NX_FLOAT
        y_pixel_size:NX_FLOAT
      monochromator:NXmonochromator
        wavelength:NX_FLOAT
        wavelength_spread:NX_FLOAT
      source:NXsource
        name:NX_CHAR
        probe:NX_CHAR
        type:NX_CHAR
    control:NXmonitor
      integral:NX_FLOAT
      mode:NX_CHAR
      preset:NX_FLOAT
    sample:NXsample
      aequatorial_angle:NX_FLOAT
      name:NX_CHAR