Let me add something here, also for people that might find this thread in the future. “Montage” in EEG/iEEG is a bit of an ambiguous term (and hence not part of the BIDS specification). it can relate to the position of electrodes and/or the referencing and/or the display.
The placement of the electrodes should (as Stefan points out) be in the
The referencing scheme that was used in the recording and hence reflected in the values in the channels in the data file is to be specified in the
(i)EEGReference field in the
_(i)eeg.json and in detail for different channels in the reference column in the
The way data is to be (or can be displayed), like in AnyWave with grouping and/or scaling channels, is not part of the specification. If you want to share that information (which I think is valuable, but possibly not so widely useable since not standard), you can give the file a name that makes most sense to you (hopefully BIDS-like) and add it to the