data folder uppermost BIDS directory, and contains all other files and folders in the BIDS hierarchy.
|dataset_description.json||[file] [json] [Required]. This file contains details of the dataset, including its "name" and the version of the BIDS protocol it is structured with ("BIDSVERSION"). May also include: License, Authors, Acknowledgements, HowToAcknowledge, Funding, ReferencesAndLinks, DatasetDOI.|
|README||[file] [plaint text] [Optional]. This is user-defined. It contains any information researchers consider necessary.|
|CHANGES||[file] [plain text] [Optional]. This file is user-defined and holds a history of major changes, updates and corrections to the dataset. It uses CPNA Changelog conventions|
|participants.tsv||[file] [tsv] [Optional]. This holds the ID of each individual in the dataset and, typically, de-identified information about each individual (e.g., age, handedness). Details useful for clinical language fMRI may also include primary language, history of language disability, past neurosurgery, and the like.|
|participants.json||[file] [json] [Optional]. This file is paired with participants.tsv and exists simply to explain what information is contained in each participants.tsv column. It is referred to as a 'Sidecar.'|
|sub-[ID]||[folder] [Required]. This folder contains all .nii images for analysis for a given patient. This is unprocessed data. Any processed data is written to a folder in derivatives. Data for one subject is required; additional folders are added for all remaining subjects.|
|sourcedata||[folder] [Optional]. This holds all data collected in its most basic, unprocessed state. This will include patient DICOMs, logfiles from run-time, and unscored behavioral data protocols.|
|derivatives||[folder] [Optional]. This folder holds the results of all processing. It contains multiple folders for different flavors of processing, such as preprocessing and then analyses. It can contain versions of these folders for each different study using the dataset.|
|code||[folder] [Optional]. This holds all dataset-related scripts.|
|stimuli||[folder] [Optional]. This folder can hold any stimuli used in the data collection for this study (e.g., fMRI tasks).|
Note: Full details available at BIDS website; the full specification is definitive.