incident_wavelength_spectrum group(???) in NXmx

[Gigarrum]

There is a group inside NXmx application definition called incident_wavelength_spectrum which, according to the docs is a NXdata group. The following topics are regards about it:

1. A documentation for it is missing
2. Should it really be a NXData group? I am really confused on why it is a NXdata group and not a field instead.
3. That group is inside NXBeam scope in the appplication definition but there is no definition for it inside NXBeam. Should it be part of NXBeam class definition or it is only a NXmx specific requirement?

[phyy-nx]

Discussion from Code Camp:

• Proposed documentation: "this group is intended for use cases that do not fit the incident_wavelength and incident_wavelength_weights fields above, perhaps for example a 2D spectrometer."
• Do a fix of shot- to-shot spacing while we are at it
• Regarding specific questions, it's an NXdata group to allow a variety of use cases and at present is only specified for NXmx.