Trying to use the schema to index some things with bids-matlab, I came across some files that I think are not covered yet.

https://github.com/bids-standard/bids-examples/tree/master/ds000248/sub-01/meg

/bids-examples/ds000248/sub-01/meg
├── sub-01_acq-calibration_meg.dat   <---- HERE
├── sub-01_acq-crosstalk_meg.fif   <---- HERE
├── sub-01_coordsystem.json
├── sub-01_task-audiovisual_run-01_channels.tsv
├── sub-01_task-audiovisual_run-01_events.tsv
├── sub-01_task-audiovisual_run-01_meg.fif
└── sub-01_task-audiovisual_run-01_meg.json

They are mentioned in the appendix.

https://bids-specification.readthedocs.io/en/stable/99-appendices/06-meg-file-formats.html#cross-talk-and-fine-calibration-files

• cross-talk file template: sub-[_ses-]_acq-crosstalk_meg.fif
• fine-calibration file template: sub-[_ses-]_acq-calibration_meg.dat

The issue now though is that in the same folder we have files with the same suffix, same extention but different set of requirements for which entities are required. @tsalo is there a precedent about this?