# subjects This object is an **array** of subjects, with information about each subject.

### JSON variables :blue\_circle: Primary key\ :red\_circle: Required\ :yellow\_circle: Computed (squirrel writer/reader should handle these variables)

Variable	Type	Default	Description (and possible values)
`AlternateIDs`	JSON array		List of alternate IDs. Comma separated.
`DateOfBirth`	date	🔴	Subject’s date of birth. Used to calculate age-at-study. Value can be `YYYY-00-00` to store year only, or `YYYY-MM-00` to store year and month only.
`Gender`	char		Gender.
`GUID`	string		Globally unique identifier, from the NIMH Data Archive (NDA).
`Ethnicity1`	string		NIH defined ethnicity: Usually `hispanic`, `non-hispanic`
`Ethnicity2`	string		NIH defined race: `americanindian`, `asian`, `black`, `hispanic`, `islander`, `white`
`Notes`	string		Notes about this subject
`Sex`	char	🔴	Sex at birth (F,M,O,U).
`SubjectID`	string	🔴 🔵	Unique ID of this subject. Each subject ID must be unique within the package.
`InterventionCount`	number	🟡	Number of intervention objects.
`ObservationCount`	number	🟡	Number of observation objects.
`StudyCount`	number	🟡	Number of studies.
`VirtualPath`	string	🟡	Relative path to the data within the package.
studies	JSON array		Array of imaging studies/sessions.
observations	JSON array		Array of observations.
interventions	JSON array		Array of interventions.

### Directory structure Files associated with this section are stored in the following directory > `/data/`