Remove "Preprocessed diffusion-weighted images"?

[Lestropie]

• Consider removing example pre-processed DWIs: should be covered by common derivatives

• Consider removing reserved JSON metadata fields, as these relate to provenance and responsibility for such should be deferred elsewhere

[Lestropie]

Options:

1. Remove "Pre-processed diffusion-weighted images" section entirely.

   Appropriate formatting of pre-processed DWI data would need to be inferred based on existing contents of the specification; e.g. file name can't be identical to the corresponding BIDS Raw file; .bvecs & .bvals are requisite.

   JSON reserved keywords based on preprocessing would be omitted. Software tools would be free to insert any information they wish into the JSON, but there would be no established dictionary of such, noting that the current example dictionary relates entirely to provenance, for which we are seeking to defer responsibility.

2. Instead provide an "example" of what pre-processed DWI might look like; e.g. could make "_desc-preproc" a RECOMMENDED. The current text jumps straight into "Multiple different versions of preprocessing can be stored for the same source data", which is an edge use case and would be the one time that the "_desc-preproc" recommendation would not suffice.

   Even if taking this option, I would personally still be recommending to omit the JSON reserved keywords.

[arokem]

I like number 2 a bit better, as I think that it eases a reader of the spec into things more gradually. I agree that we would want to omit the JSON keywords, since that is indicative of provenance.

[neurolabusc]

If the section is retained, the filename extensions .bvecs and .bvals should be renamed .bvec and .bval to be consistent with the existing BIDS specification.