Cyril Pernet

ah of course @robertoostenveld was on the case :-) Having browsed the different items mentioned above, I do see an issue with name inconsistency I do like your proposal [593](https://github.com/bids-standard/bids-specification/issues/593)...

I did :-) and instrument/data type sounds good to me (still not defining what modality would be after that)

should work sub-xx_acq-MPRAGEMOCOOFF_task-STILL_T1w.nii.gz sub-xx_acq-MPRAGEMOCOOFF_rec-RR_task-STILL_T1w.nii.gz sub-xx_acq-MPRAGEMOCOON_task-STILL_T1w.nii.gz sub-xx_acq-MPRAGEMOCOON_rec-RR_task-STILL_T1w.nii.gz sub-xx_acq-MPRAGEMOCOOFF_task-NOD_T1w.nii.gz sub-xx_acq-MPRAGEMOCOOFF_rec-RR_task-NOD_T1w.nii.gz sub-xx_acq-MPRAGEMOCOON_task-NOD_T1w.nii.gz sub-xx_acq-MPRAGEMOCOON_rec-RR_task-NOD_T1w.nii.gz sub-xx_acq-MPRAGEMOCOOFF_task-SHAKE_T1w.nii.gz sub-xx_acq-MPRAGEMOCOOFF_rec-RR_task-SHAKE_T1w.nii.gz sub-xx_acq-MPRAGEMOCOON_task-SHAKE_T1w.nii.gz sub-xx_acq-MPRAGEMOCOON_rec-RR_task-SHAKE_T1w.nii.gz got to see how the validator behaves?

oh `ks` :-) we could do a PR to the [MRI spec](https://github.com/bids-standard/bids-specification/blob/master/src/04-modality-specific-files/01-magnetic-resonance-imaging-data.md?plain=1) there is plenty of physics there now with ASL so adding `ks` wouldn't look odd. Would that go...

the one who needs it! @melanieganz :-; ahahah

I'm also all for @yarikoptic approach. Note that electrophys derivatives have the same issue with processed data typically in a different format, and we need a common ground. I discussed...

as an additional point, I was wondering if you should state somewhere in the specification that any derived data that can be stored using the native format must do so...

Following @GaelVaroquaux 'weak' opinion :-) if maintenance is an issue we should not go for HDF5. I have nothing against numpy array but you have to consider that SPM is...

> as an additional point, I was wondering if you should state somewhere in the specification that any derived data that can be stored using the native format must do...

@effigies isn't `OPTIONAL but REQUIRED if ` similar to what is already used for ['NonlinearGradientCorrection'](https://bids-specification.readthedocs.io/en/stable/04-modality-specific-files/01-magnetic-resonance-imaging-data.html#sequence-specifics) which then would make sense to use as a rule for conditional stuff -- although...