Table 4.

Mechanisms HED annotations in BIDS .json and .tsv metadata files. Many datasets may need only one …events.json file placed in the top (Dataset) level folder. Note: …events.json files may also be placed at intermediate levels of the BIDS dataset to annotate items specific to a participant, session, or modality.

BIDS folder level	Information file	Function
Dataset	…events.json	Provides descriptions of the columns that are applicable to all the …events.tsv files in the dataset. [The ‘HED’ keys in this JSON dictionary link HED annotations to values in the events files.]
	participants.tsv	Lists the participants. [A HED column may be used to add participant-specific information in HED annotation.]
Subject	…sessions.tsv	Lists the sessions per participant. [A HED column may be used to add session-specific information in HED annotation.]
Session	…scans.tsv	Lists the scans in the session (optional). [A HED column may be used to add scan-specific information in HED annotation.]
Modality(Scan)	…events.tsv	Lists the events in the scan (run). The column meanings and associated HED tags are given in the dataset-level …events.json file or other applicable …events.json files in the hierarchy. [A HED column in …events.tsv gives event-specific information in HED annotation.]