In BIDS 1.5.0,

Key name	Requirement level	Data type	Description
IntendedFor	RECOMMENDED	[string][]	This can be an MRI/CT or a file containing the operative photo, x-ray or drawing with path relative to the project folder. If only a surface reconstruction is available, this should point to the surface reconstruction file. Note that this file should have the same coordinate system specified in iEEGCoordinateSystem. For example, T1: sub-<label>/ses-<label>/anat/sub-01_T1w.nii.gz Surface: /derivatives/surfaces/sub-<label>/ses-<label>/anat/sub-01_T1w_pial.R.surf.gii Operative photo: /sub-<label>/ses-<label>/ieeg/sub-0001_ses-01_acq-photo1_photo.jpg Talairach: /derivatives/surfaces/sub-Talairach/ses-01/anat/sub-Talairach_T1w_pial.R.surf.gii

Now:

Key name	Requirement level	Data type	Description
IntendedFor	OPTIONAL	string or array of strings	The paths to files for which the associated file is intended to be used. Contains one or more filenames with paths relative to the participant subdirectory. Paths need to use forward slashes instead of backward slashes, regardless of operating system. If only a surface reconstruction is available, this should point to the surface reconstruction file. Note that this file should have the same coordinate system specified in iEEGCoordinateSystem. For example, T1: 'sub-/ses-/anat/sub-01_T1w.nii.gz' Surface: '/derivatives/surfaces/sub-/ses-/anat/sub-01_hemi-R_desc-T1w_pial.surf.gii' Operative photo: '/sub-/ses-/ieeg/sub-0001_ses-01_acq-photo1_photo.jpg' Talairach: '/derivatives/surfaces/sub-Talairach/ses-01/anat/sub-Talairach_hemi-R_pial.surf.gii'

So we've gone from dataset-relative to participant-relative, while the examples remain dataset relative.

Is this a known issue? Are we intending to restore the previous definition, or are iEEG (and any other BEPs that used dataset-relative) okay with the backwards incompatibility issue?