[FIX] Permitting desc for channels and events

[neuromechanist]

Fixes #2029, to accommodate the desc entity (based on the current derivative specifications, for channels, electrodes, coordsystem and events files.

I was not sure if adding description to channels.channel would be inherited to other special cases, such as channels.channels__motion, so I explicitly included those in the schema as well.

@effigies, I appreciate your insights.

[neuromechanist]

cc: @arnodelorme

[effigies]

This looks reasonable to me. I pushed a fix that I hope resolves the CI, but we'll see.

It seems raw electrodes files already support space, but should derivative coordsystems? I ask purely out of ignorance; if the answer is no, I'm happy to defer to those who use these data.

[neuromechanist]

Thanks, and sorry for the oversight.

The EEG specifications does allow space, although does not describe space at all, nor there are examples for it.

iEEG provides a use (and examples) for space, specifying which "space" (that is coordinate system) the sensors/electrodes are placed in, for instance, MNI, Talairach, etc. With this use, space should be available for both electrodes and coordsystem as a raw entity. I can see that some people may change the space to a more "convenient one" for their use during processing and share the data in a new space as a derivative, but, that use case already will have a change in the space label as well as hopefully a description. I am not sure if this answers your question.

[tsalo]

The changes make sense to me

[effigies]

Since this is a fix to the schema and not something new to BIDS, this targets the maint/1.10.0 branch. We will make a new schema release.