metadata.yaml

---
# This file defines valid BIDS metadata fields.
# These definitions include the field names, their descriptions, and valid values.
# This file **does not** define how and when metadata fields can be used with a given file.
ACCELChannelCount:
  name: ACCELChannelCount
  display_name: Accelerometer channel count
  description: |
    Number of accelerometer channels.
  type: integer
  minimum: 0
Acknowledgements:
  name: Acknowledgements
  display_name: Acknowledgements
  description: |
    Text acknowledging contributions of individuals or institutions beyond
    those listed in Authors or Funding.
  type: string
AcquisitionDuration:
  name: AcquisitionDuration
  display_name: Acquisition Duration
  description: |
    Duration (in seconds) of volume acquisition.
    Corresponds to DICOM Tag 0018, 9073 `Acquisition Duration`.
    This field is mutually exclusive with `"RepetitionTime"`.
  type: number
  exclusiveMinimum: 0
  unit: s
AcquisitionMode:
  name: AcquisitionMode
  display_name: Acquisition Mode
  description: |
    Type of acquisition of the PET data (for example, `"list mode"`).
  type: string
AcquisitionVoxelSize:
  name: AcquisitionVoxelSize
  display_name: Acquisition Voxel Size
  description: |
    An array of numbers with a length of 3, in millimeters.
    This parameter denotes the original acquisition voxel size,
    excluding any inter-slice gaps and before any interpolation or resampling
    within reconstruction or image processing.
    Any point spread function effects, for example due to T2-blurring,
    that would decrease the effective resolution are not considered here.
  type: array
  minItems: 3
  maxItems: 3
  items:
    type: number
    exclusiveMinimum: 0
    unit: mm
Anaesthesia:
  name: Anaesthesia
  display_name: Anaesthesia
  description: |
    Details of anaesthesia used, if any.
  type: string
AnalyticalApproach:
  name: AnalyticalApproach
  display_name: Analytical Approach
  description: |
    Methodology or methodologies used to analyse the `"GeneticLevel"`.
    Values MUST be taken from the
    [database of Genotypes and Phenotypes
    (dbGaP)](https://www.ncbi.nlm.nih.gov/gap/advanced)
    under /Study/Molecular Data Type (for example, SNP Genotypes (Array) or
    Methylation (CpG).
  anyOf:
    - type: string
    - type: array
      items:
        type: string
AnatomicalImage:
  name: AnatomicalImage
  display_name: Anatomical Image
  description: |
    The path(s) to the anatomical MR image file(s), if present,
    to which the associated MRS data file corresponds.
    Contains one or more [BIDS URIs](SPEC_ROOT/common-principles.md#bids-uri).
  anyOf:
    - type: string
    - type: array
      items:
        type: string
AnatomicalLandmarkCoordinateSystem:
  name: AnatomicalLandmarkCoordinateSystem
  display_name: Anatomical Landmark Coordinate System
  description: |
    Defines the coordinate system for the anatomical landmarks.
    See the [Coordinate Systems Appendix](SPEC_ROOT/appendices/coordinate-systems.md)
    for a list of restricted keywords for coordinate systems.
    If `"Other"`, provide definition of the coordinate system in
    `"AnatomicalLandmarkCoordinateSystemDescription"`.
  anyOf:
    - $ref: objects.metadata._MEGCoordSys
    - $ref: objects.metadata._EEGCoordSys
    - $ref: objects.metadata._StandardTemplateCoordSys
    - $ref: objects.metadata._StandardTemplateDeprecatedCoordSys
AnatomicalLandmarkCoordinateSystemDescription:
  name: AnatomicalLandmarkCoordinateSystemDescription
  display_name: Anatomical Landmark Coordinate System Description
  description: |
    Free-form text description of the coordinate system.
    May also include a link to a documentation page or paper describing the
    system in greater detail.
  type: string
AnatomicalLandmarkCoordinateUnits:
  name: AnatomicalLandmarkCoordinateUnits
  display_name: Anatomical Landmark Coordinate Units
  description: |
    Units of the coordinates of `"AnatomicalLandmarkCoordinateSystem"`.
  type: string
  enum:
    - m
    - mm
    - cm
    - n/a
AnatomicalLandmarkCoordinates:
  name: AnatomicalLandmarkCoordinates
  display_name: Anatomical Landmark Coordinates
  description: |
    Key-value pairs of the labels and 3-D digitized locations of anatomical landmarks,
    interpreted following the `"AnatomicalLandmarkCoordinateSystem"`
    (for example, `{"NAS": [12.7,21.3,13.9], "LPA": [5.2,11.3,9.6],
    "RPA": [20.2,11.3,9.1]}`.
    Each array MUST contain three numeric values corresponding to x, y, and z
    axis of the coordinate system in that exact order.
  type: object
  additionalProperties:
    type: array
    items:
      type: number
    minItems: 3
    maxItems: 3
# Redefinition of AnatomicalLandmarkCoordinates for MRI data
AnatomicalLandmarkCoordinates__mri:
  name: AnatomicalLandmarkCoordinates
  display_name: Anatomical Landmark Coordinates
  description: |
    Key-value pairs of any number of additional anatomical landmarks and their
    coordinates in voxel units (where first voxel has index 0,0,0)
    relative to the associated anatomical MRI
    (for example, `{"AC": [127,119,149], "PC": [128,93,141],
    "IH": [131,114,206]}`, or `{"NAS": [127,213,139], "LPA": [52,113,96],
    "RPA": [202,113,91]}`).
    Each array MUST contain three numeric values corresponding to x, y, and z
    axis of the coordinate system in that exact order.
  type: object
  additionalProperties:
    type: array
    items:
      type: number
    minItems: 3
    maxItems: 3
ArterialSpinLabelingType:
  name: ArterialSpinLabelingType
  display_name: Arterial Spin Labeling Type
  description: |
    The arterial spin labeling type.
  type: string
  enum:
    - CASL
    - PCASL
    - PASL
AssociatedEmptyRoom:
  name: AssociatedEmptyRoom
  display_name: Associated Empty Room
  description: |
    One or more [BIDS URIs](SPEC_ROOT/common-principles.md#bids-uri)
    pointing to empty-room file(s) associated with the subject's MEG recording.
    Using forward-slash separated paths relative to the dataset root is
    [DEPRECATED](SPEC_ROOT/common-principles.md#definitions).
  anyOf:
    - type: array
      items:
        anyOf:
          - type: string
            format: dataset_relative
          - type: string
            format: bids_uri
    - type: string
      format: dataset_relative
    - type: string
      format: bids_uri
Atlas:
  name: Atlas
  display_name: Atlas
  description: |
    Which atlas (if any) was used to generate the mask.
  type: string
AttenuationCorrection:
  name: AttenuationCorrection
  display_name: Attenuation Correction
  description: |
    Short description of the attenuation correction method used.
  type: string
AttenuationCorrectionMethodReference:
  name: AttenuationCorrectionMethodReference
  display_name: Attenuation Correction Method Reference
  description: |
    Reference paper for the attenuation correction method used.
  type: string
Authors:
  name: Authors
  display_name: Authors
  description: |
    List of individuals who contributed to the creation/curation of the dataset.
  type: array
  items:
    type: string
B0FieldIdentifier:
  name: B0FieldIdentifier
  display_name: B0 Field Identifier
  description: |
    The presence of this key states that this particular 3D or 4D image MAY be
    used for fieldmap estimation purposes.
    Each `"B0FieldIdentifier"` MUST be a unique string within one participant's tree,
    shared only by the images meant to be used as inputs for the estimation of a
    particular instance of the *B<sub>0</sub> field* estimation.
    It is RECOMMENDED to derive this identifier from DICOM Tags, for example,
    DICOM tag 0018, 1030 `Protocol Name`, or DICOM tag 0018, 0024 `Sequence Name`
    when the former is not defined (for example, in GE devices.)
  anyOf:
    - type: string
    - type: array
      items:
        type: string
B0FieldSource:
  name: B0FieldSource
  display_name: B0 Field Source
  description: |
    At least one existing `"B0FieldIdentifier"` defined by images in the
    participant's tree.
    This field states the *B<sub>0</sub> field* estimation designated by the
    `"B0FieldIdentifier"` that may be used to correct the dataset for distortions
    caused by B<sub>0</sub> inhomogeneities.
    `"B0FieldSource"` and `"B0FieldIdentifier"` MAY both be present for images that
    are used to estimate their own B<sub>0</sub> field, for example, in "pepolar"
    acquisitions.
  anyOf:
    - type: string
    - type: array
      items:
        type: string
B0ShimmingTechnique:
  name: B0ShimmingTechnique
  display_name: B0 Shimming Technique
  description: |
    The technique used to shim the *B<sub>0</sub>* field (for example, `"FASTMAP"`).
  type: string
B1ShimmingTechnique:
  name: B1ShimmingTechnique
  display_name: B1 Shimming Technique
  description: |
    The technique used to shim the *B<sub>1</sub>* field (for example, `"Simple phase align"`).
  type: string
BIDSVersion:
  name: BIDSVersion
  display_name: BIDS Version
  description: |
    The version of the BIDS standard that was used.
  type: string
BackgroundSuppression:
  name: BackgroundSuppression
  display_name: Background Suppression
  description: |
    Boolean indicating if background suppression is used.
  type: boolean
BackgroundSuppressionNumberPulses:
  name: BackgroundSuppressionNumberPulses
  display_name: Background Suppression Number Pulses
  description: |
    The number of background suppression pulses used.
    Note that this excludes any effect of background suppression pulses applied
    before the labeling.
  type: number
  minimum: 0
BackgroundSuppressionPulseTime:
  name: BackgroundSuppressionPulseTime
  display_name: Background Suppression Pulse Time
  description: |
    Array of numbers containing timing, in seconds,
    of the background suppression pulses with respect to the start of the
    labeling.
    In case of multi-PLD with different background suppression pulse times,
    only the pulse time of the first PLD should be defined.
  type: array
  items:
    type: number
    minimum: 0
    unit: s
BasedOn:
  name: BasedOn
  display_name: Based On
  description: |
    List of files in a file collection to generate the map.
    Fieldmaps are also listed, if involved in the processing.
    This field is DEPRECATED, and this metadata SHOULD be recorded in the
    `Sources` field using [BIDS URIs](SPEC_ROOT/common-principles.md#bids-uri)
    to distinguish sources from different datasets.
  anyOf:
    - type: string
      format: participant_relative
    - type: array
      items:
        type: string
        format: participant_relative
BloodDensity:
  name: BloodDensity
  display_name: Blood Density
  description: |
    Measured blood density. Unit of blood density should be in `"g/mL"`.
  type: number
  unit: g/mL
BodyPart:
  name: BodyPart
  display_name: Body Part
  description: |
    Body part of the organ / body region scanned.
  type: string
BodyPartDetails:
  name: BodyPartDetails
  display_name: Body Part Details
  description: |
    Additional details about body part or location (for example: `"corpus callosum"`).
  type: string
BodyPartDetailsOntology:
  name: BodyPartDetailsOntology
  display_name: Body Part Details Ontology
  description: |
    [URI](SPEC_ROOT/common-principles.md#uniform-resource-indicator) of ontology used for
    BodyPartDetails (for example: `"https://www.ebi.ac.uk/ols/ontologies/uberon"`).
  type: string
  format: uri
BolusCutOffDelayTime:
  name: BolusCutOffDelayTime
  display_name: Bolus Cut Off Delay Time
  description: |
    Duration between the end of the labeling and the start of the bolus cut-off
    saturation pulse(s), in seconds.
    This can be a number or array of numbers, of which the values must be
    non-negative and monotonically increasing, depending on the number of bolus
    cut-off saturation pulses.
    For Q2TIPS, only the values for the first and last bolus cut-off saturation
    pulses are provided.
    Based on DICOM Tag 0018, 925F `ASL Bolus Cut-off Delay Time`.
  anyOf:
    - type: number
      minimum: 0
      unit: s
    - type: array
      items:
        type: number
        unit: s
        minimum: 0
BolusCutOffFlag:
  name: BolusCutOffFlag
  display_name: Bolus Cut Off Flag
  description: |
    Boolean indicating if a bolus cut-off technique is used.
    Corresponds to DICOM Tag 0018, 925C `ASL Bolus Cut-off Flag`.
  type: boolean
BolusCutOffTechnique:
  name: BolusCutOffTechnique
  display_name: Bolus Cut Off Technique
  description: |
    Name of the technique used, for example `"Q2TIPS"`, `"QUIPSS"`, `"QUIPSSII"`.
    Corresponds to DICOM Tag 0018, 925E `ASL Bolus Cut-off Technique`.
  type: string
BrainLocation:
  name: BrainLocation
  display_name: Brain Location
  description: |
    Refers to the location in space of the `"TissueOrigin"`.
    Values may be an MNI coordinate,
    a label taken from the
    [Allen Brain Atlas](https://atlas.brain-map.org/atlas?atlas=265297125&plate=\
    112360888&structure=4392&x=40348.15104166667&y=46928.75&zoom=-7&resolution=\
    206.60&z=3),
    or layer to refer to layer-specific gene expression,
    which can also tie up with laminar fMRI.
  type: string
CASLType:
  name: CASLType
  display_name: CASL Type
  description: |
    Describes if a separate coil is used for labeling.
  type: string
  enum:
    - single-coil
    - double-coil
CapManufacturer:
  name: CapManufacturer
  display_name: Cap Manufacturer
  description: |
    Name of the cap manufacturer (for example, `"EasyCap"`).
  type: string
CapManufacturersModelName:
  name: CapManufacturersModelName
  display_name: Cap Manufacturers Model Name
  description: |
    Manufacturer's designation of the cap model
    (for example, `"actiCAP 64 Ch Standard-2"`).
  type: string
CellType:
  name: CellType
  display_name: Cell Type
  description: |
    Describes the type of cell analyzed.
    Values SHOULD come from the
    [cell ontology](http://obofoundry.org/ontology/cl.html).
  type: string
ChemicalShiftOffset:
  name: ChemicalShiftOffset
  display_name: Chemical Shift Offset
  description: |
    The chemical shift at the center of `"SpectralWidth"` corresponding to 0 Hz,
    specified in ppm (for example, `4.65`).
  type: number
ChemicalShiftReference:
  name: ChemicalShiftReference
  display_name: Chemical Shift Reference
  description: |
    The chemical shift at the transmitter frequency, specified in ppm (for example, `2.68`).
    Corresponds to DICOM Tag 0018, 9053 `Chemical Shift Reference`.
  type: number
ChunkTransformationMatrix:
  name: ChunkTransformationMatrix
  display_name: Chunk Transformation Matrix
  description: |
    3x3 or 4x4 affine transformation matrix describing spatial chunk transformation,
    for 2D and 3D respectively (for examples: `[[2, 0, 0], [0, 3, 0], [0, 0, 1]]`
    in 2D for 2x and 3x scaling along the first and second axis respectively; or
    `[[1, 0, 0, 0], [0, 2, 0, 0], [0, 0, 3, 0], [0, 0, 0, 1]]` in 3D for 2x and 3x
    scaling along the second and third axis respectively).
    Note that non-spatial dimensions like time and channel are not included in the
    transformation matrix.
  anyOf:
    - type: array
      minItems: 3
      maxItems: 3
      items:
        type: array
        minItems: 3
        maxItems: 3
        items:
          type: number
    - type: array
      minItems: 4
      maxItems: 4
      items:
        type: array
        minItems: 4
        maxItems: 4
        items:
          type: number
ChunkTransformationMatrixAxis:
  name: ChunkTransformationMatrixAxis
  display_name: Chunk Transformation Matrix Axis
  description: |
    Describe the axis of the ChunkTransformationMatrix
    (for examples: `["X", "Y"]` or `["Z", "Y", "X"]`).
  type: array
  minItems: 2
  maxItems: 3
  items:
    type: string
Code:
  name: Code
  display_name: Code
  description: |
    [URI](SPEC_ROOT/common-principles.md#uniform-resource-indicator)
    of the code used to present the stimuli.
    Persistent identifiers such as DOIs are preferred.
    If multiple versions of code may be hosted at the same location,
    revision-specific URIs are recommended.
  type: string
  format: uri
CogAtlasID:
  name: CogAtlasID
  display_name: Cognitive Atlas ID
  description: |
    [URI](SPEC_ROOT/common-principles.md#uniform-resource-indicator)
    of the corresponding [Cognitive Atlas](https://www.cognitiveatlas.org/)
    Task term.
  type: string
  format: uri
CogPOID:
  name: CogPOID
  display_name: Cognitive Paradigm Ontology ID
  description: |
    [URI](SPEC_ROOT/common-principles.md#uniform-resource-indicator)
    of the corresponding [CogPO](http://www.cogpo.org/) term.
  type: string
  format: uri
CoilCombinationMethod:
  name: CoilCombinationMethod
  display_name: Coil Combination Method
  description: |
    Almost all fMRI studies using phased-array coils use root-sum-of-squares
    (rSOS) combination, but other methods exist.
    The image reconstruction is changed by the coil combination method
    (as for the matrix coil mode above),
    so anything non-standard should be reported.
  type: string
Columns:
  name: Columns
  display_name: Columns
  description: |
    Names of columns in file.
  type: array
  items:
    type: string
ContinuousHeadLocalization:
  name: ContinuousHeadLocalization
  display_name: Continuous Head Localization
  description: |
    `true` or `false` value indicating whether continuous head localisation
    was performed.
  type: boolean
ContrastBolusIngredient:
  name: ContrastBolusIngredient
  display_name: Contrast Bolus Ingredient
  description: |
    Active ingredient of agent.
    Corresponds to DICOM Tag 0018, 1048 `Contrast/Bolus Ingredient`.
  type: string
  enum:
    - IODINE
    - GADOLINIUM
    - CARBON DIOXIDE
    - BARIUM
    - XENON
DCOffsetCorrection:
  name: DCOffsetCorrection
  display_name: DC Offset Correction
  description: |
    A description of the method (if any) used to correct for a DC offset.
    If the method used was subtracting the mean value for each channel,
    use "mean".
  type: string
DatasetDOI:
  name: DatasetDOI
  display_name: DatasetDOI
  description: |
    The Digital Object Identifier of the dataset (not the corresponding paper).
    DOIs SHOULD be expressed as a valid
    [URI](SPEC_ROOT/common-principles.md#uniform-resource-indicator);
    bare DOIs such as `10.0.2.3/dfjj.10` are
    [DEPRECATED](SPEC_ROOT/common-principles.md#definitions).
  type: string
  format: uri
DatasetLinks:
  name: DatasetLinks
  display_name: Dataset Links
  description: |
    Used to map a given `<dataset-name>` from a [BIDS URI](SPEC_ROOT/common-principles.md#bids-uri)
    of the form `bids:<dataset-name>:path/within/dataset` to a local or remote location.
    The `<dataset-name>`: `""` (an empty string) is a reserved keyword that MUST NOT be a key in
    `DatasetLinks` (example: `bids::path/within/dataset`).
  type: object
  additionalProperties:
    type: string
    format: uri
DatasetType:
  name: DatasetType
  display_name: Dataset Type
  description: |
    The interpretation of the dataset.
    For backwards compatibility, the default value is `"raw"`.
  type: string
  enum:
    - raw
    - derivative
DecayCorrectionFactor:
  name: DecayCorrectionFactor
  display_name: Decay Correction Factor
  description: |
    Decay correction factor for each frame.
  type: array
  items:
    type: number
DelayAfterTrigger:
  name: DelayAfterTrigger
  display_name: Delay After Trigger
  description: |
    Duration (in seconds) from trigger delivery to scan onset.
    This delay is commonly caused by adjustments and loading times.
    This specification is entirely independent of
    `"NumberOfVolumesDiscardedByScanner"` or `"NumberOfVolumesDiscardedByUser"`,
    as the delay precedes the acquisition.
  type: number
  unit: s
DelayTime:
  name: DelayTime
  display_name: Delay Time
  description: |
    User specified time (in seconds) to delay the acquisition of data for the
    following volume.
    If the field is not present it is assumed to be set to zero.
    Corresponds to Siemens CSA header field `lDelayTimeInTR`.
    This field is REQUIRED for sparse sequences using the `"RepetitionTime"` field
    that do not have the `"SliceTiming"` field set to allowed for accurate
    calculation of "acquisition time".
    This field is mutually exclusive with `"VolumeTiming"`.
  type: number
  unit: s
Density:
  name: Density
  display_name: Density
  description: |
    Specifies the interpretation of the density keyword.
    If an object is used, then the keys should be values for the `den` entity
    and values should be descriptions of those `den` values.
  anyOf:
    - type: string
    - type: object
      additionalProperties:
        type: string
Derivative:
  name: Derivative
  display_name: Derivative
  description: |
    Indicates that values in the corresponding column are transformations of values
    from other columns (for example a summary score based on a subset of items in a
    questionnaire).
  type: boolean
Description:
  name: Description
  display_name: Description
  description: |
    Free-form natural language description.
  type: string
DetectorType:
  name: DetectorType
  display_name: Detector Type
  description: |
    Type of detector. This is a free form description with the following suggested terms:
    `"SiPD"`, `"APD"`. Preferably a specific model/part number is supplied.
    If individual channels have different `DetectorType`,
    then the field here should be specified as `"mixed"`
    and this column should be included in `optodes.tsv`.
  anyOf:
    - type: string
      format: unit
    - type: string
      enum:
        - mixed
DeviceSerialNumber:
  name: DeviceSerialNumber
  display_name: Device Serial Number
  description: |
    The serial number of the equipment that produced the measurements.
    A pseudonym can also be used to prevent the equipment from being
    identifiable, so long as each pseudonym is unique within the dataset.
  type: string
DewarPosition:
  name: DewarPosition
  display_name: Dewar Position
  description: |
    Position of the dewar during the MEG scan:
    `"upright"`, `"supine"` or `"degrees"` of angle from vertical:
    for example on CTF systems, `"upright=15°, supine=90°"`.
  type: string
DigitizedHeadPoints:
  name: DigitizedHeadPoints
  display_name: Digitized Head Points
  description: |
    `true` or `false` value indicating whether head points outlining the
    scalp/face surface are contained within this recording.
  type: boolean
DigitizedHeadPoints__coordsystem:
  name: DigitizedHeadPoints
  display_name: Digitized Head Points
  description: |
    Relative path to the file containing the locations of digitized head points
    collected during the session (for example, `"sub-01_headshape.pos"`).
    RECOMMENDED for all MEG systems, especially for CTF and BTi/4D.
    For Neuromag/Elekta/MEGIN, the head points will be stored in the `.fif` file.
  type: string
  format: file_relative
DigitizedHeadPointsCoordinateSystem:
  name: DigitizedHeadPointsCoordinateSystem
  display_name: Digitized Head Points Coordinate System
  description: |
    Defines the coordinate system for the digitized head points.
    See the
    [Coordinate Systems Appendix](SPEC_ROOT/appendices/coordinate-systems.md)
    for a list of restricted keywords for coordinate systems.
    If `"Other"`, provide definition of the coordinate system in
    `"DigitizedHeadPointsCoordinateSystemDescription"`.
  anyOf:
    - $ref: objects.metadata._MEGCoordSys
    - $ref: objects.metadata._EEGCoordSys
    - $ref: objects.metadata._StandardTemplateCoordSys
    - $ref: objects.metadata._StandardTemplateDeprecatedCoordSys
DigitizedHeadPointsCoordinateSystemDescription:
  name: DigitizedHeadPointsCoordinateSystemDescription
  display_name: Digitized Head Points Coordinate System Description
  description: |
    Free-form text description of the coordinate system.
    May also include a link to a documentation page or paper describing the
    system in greater detail.
  type: string
DigitizedHeadPointsCoordinateUnits:
  name: DigitizedHeadPointsCoordinateUnits
  display_name: Digitized Head Points Coordinate Units
  description: |
    Units of the coordinates of `"DigitizedHeadPointsCoordinateSystem"`.
  type: string
  enum:
    - m
    - mm
    - cm
    - n/a
DigitizedLandmarks:
  name: DigitizedLandmarks
  display_name: Digitized Landmarks
  description: |
    `true` or `false` value indicating whether anatomical landmark points
    (fiducials) are contained within this recording.
  type: boolean
DispersionConstant:
  name: DispersionConstant
  display_name: Dispersion Constant
  description: |
    External dispersion time constant resulting from tubing in default unit
    seconds.
  type: number
  unit: s
DispersionCorrected:
  name: DispersionCorrected
  display_name: Dispersion Corrected
  description: |
    Boolean flag specifying whether the blood data have been dispersion-corrected.
    NOTE: not customary for manual samples, and hence should be set to `false`.
  type: boolean
DoseCalibrationFactor:
  name: DoseCalibrationFactor
  display_name: Dose Calibration Factor
  description: |
    Multiplication factor used to transform raw data (in counts/sec) to meaningful unit (Bq/ml).
    Corresponds to DICOM Tag 0054, 1322 `Dose Calibration Factor`.
  type: number
DwellTime:
  name: DwellTime
  display_name: Dwell Time
  description: |
    Actual dwell time (in seconds) of the receiver per point in the readout
    direction, including any oversampling.
    For Siemens, this corresponds to DICOM field 0019, 1018 (in ns).
    This value is necessary for the optional readout distortion correction of
    anatomicals in the HCP Pipelines.
    It also usefully provides a handle on the readout bandwidth,
    which isn't captured in the other metadata tags.
    Not to be confused with `"EffectiveEchoSpacing"`, and the frequent mislabeling
    of echo spacing (which is spacing in the phase encoding direction) as
    "dwell time" (which is spacing in the readout direction).
  type: number
  unit: s
ECGChannelCount:
  name: ECGChannelCount
  display_name: ECG Channel Count
  description: |
    Number of ECG channels.
  type: integer
  minimum: 0
ECOGChannelCount:
  name: ECOGChannelCount
  display_name: ECOG Channel Count
  description: |
    Number of ECoG channels.
  type: integer
  minimum: 0
EEGChannelCount:
  name: EEGChannelCount
  display_name: EEG Channel Count
  description: |
    Number of EEG channels recorded simultaneously (for example, `21`).
  type: integer
  minimum: 0
EEGCoordinateSystem:
  name: EEGCoordinateSystem
  display_name: EEG Coordinate System
  description: |
    Defines the coordinate system for the EEG sensors.

    See the
    [Coordinate Systems Appendix](SPEC_ROOT/appendices/coordinate-systems.md)
    for a list of restricted keywords for coordinate systems.
    If `"Other"`, provide definition of the coordinate system in
    `EEGCoordinateSystemDescription`.
  anyOf:
    - $ref: objects.metadata._MEGCoordSys
    - $ref: objects.metadata._EEGCoordSys
    - $ref: objects.metadata._StandardTemplateCoordSys
    - $ref: objects.metadata._StandardTemplateDeprecatedCoordSys
EEGCoordinateSystemDescription:
  name: EEGCoordinateSystemDescription
  display_name: EEG Coordinate System Description
  description: |
    Free-form text description of the coordinate system.
    May also include a link to a documentation page or paper describing the
    system in greater detail.
  type: string
EEGCoordinateUnits:
  name: EEGCoordinateUnits
  display_name: EEG Coordinate Units
  description: |
    Units of the coordinates of `EEGCoordinateSystem`.
  type: string
  enum:
    - m
    - mm
    - cm
    - n/a
EEGGround:
  name: EEGGround
  display_name: EEG Ground
  description: |
    Description of the location of the ground electrode
    (for example, `"placed on right mastoid (M2)"`).
  type: string
EEGPlacementScheme:
  name: EEGPlacementScheme
  display_name: EEG Placement Scheme
  description: |
    Placement scheme of EEG electrodes.
    Either the name of a standardized placement system (for example, `"10-20"`)
    or a list of standardized electrode names (for example, `["Cz", "Pz"]`).
  type: string
EEGReference:
  name: EEGReference
  display_name: EEG Reference
  description: |
    General description of the reference scheme used and (when applicable) of
    location of the reference electrode in the raw recordings
    (for example, `"left mastoid"`, `"Cz"`, `"CMS"`).
    If different channels have a different reference,
    this field should have a general description and the channel specific
    reference should be defined in the `channels.tsv` file.
  type: string
EMGChannelCount:
  name: EMGChannelCount
  display_name: EMG Channel Count
  description: |
    Number of EMG channels.
  type: integer
  minimum: 0
EOGChannelCount:
  name: EOGChannelCount
  display_name: EOG Channel Count
  description: |
    Number of EOG channels.
  type: integer
  minimum: 0
EchoAcquisition:
  name: EchoAcquisition
  display_name: Echo Acquisition
  description: |
    How the detected echo was acquired when the analog-to-digital converter was turned on.
    For example, `"Half echo"`, `"Full echo"`.
  type: string
EchoTime:
  name: EchoTime
  display_name: Echo Time
  description: |
    The echo time (TE) for the acquisition, specified in seconds.
    Corresponds to DICOM Tag 0018, 0081 `Echo Time`
    (please note that the DICOM term is in milliseconds not seconds).
    The data type number may apply to files from any MRI modality concerned with
    a single value for this field, or to the files in a
    [file collection](SPEC_ROOT/appendices/file-collections.md)
    where the value of this field is iterated using the
    [`echo` entity](SPEC_ROOT/appendices/entities.md#echo).
  anyOf:
    - type: number
      unit: s
      exclusiveMinimum: 0
    - type: array
      items:
        type: number
        unit: s
        exclusiveMinimum: 0
EchoTime1:
  name: EchoTime1
  display_name: Echo Time1
  description: |
    The time (in seconds) when the first (shorter) echo occurs.
  type: number
  unit: s
  exclusiveMinimum: 0
EchoTime2:
  name: EchoTime2
  display_name: Echo Time2
  description: |
    The time (in seconds) when the second (longer) echo occurs.
  type: number
  unit: s
  exclusiveMinimum: 0
# Redefinition of EchoTime for fieldmap data
EchoTime__fmap:
  name: EchoTime
  display_name: Echo Time
  description: |
    The time (in seconds) when the echo corresponding to this map was acquired.
  type: number
  unit: s
  exclusiveMinimum: 0
EditCondition:
  name: EditCondition
  display_name: Editing Condition
  description: |
    If spectral editing was applied, this lists the application order of `"EditPulse"`.
    For example, `["ON", "OFF"]` for a MEGA-edited experiment or
    `["A", "B", "C", "D"]` for a HERMES-edited experiment.
  anyOf:
    - type: string
    - type: array
      items:
        type: string
EditPulse:
  name: EditPulse
  display_name: Editing Pulse
  description: |
    If spectral editing was applied, this details the editing parameters.
    For example:
    `{"ON": {"FrequencyOffset": 1.9, "PulseDuration": 16},
    "OFF": {"FrequencyOffset": 7.5, "PulseDuration": 16}}`.
  anyOf:
    - type: object
      additionalProperties:
        type: object
EditTarget:
  name: EditTarget
  display_name: Editing Target
  description: |
    If spectral editing was applied, this describes the metabolites that were selectively targeted
    (for example, `"GABA"` or `"Lac"`).
    If multiple metabolites were targeted (for example, in a HERMES acquisition),
    an array can be used: `["GABA", "GSH"]`.
  anyOf:
    - type: string
    - type: array
      items:
        type: string
EffectiveEchoSpacing:
  name: EffectiveEchoSpacing
  display_name: Effective Echo Spacing
  description: |
    The "effective" sampling interval, specified in seconds,
    between lines in the phase-encoding direction,
    defined based on the size of the reconstructed image in the phase direction.
    It is frequently, but incorrectly, referred to as "dwell time"
    (see the `"DwellTime"` parameter for actual dwell time).
    It is required for unwarping distortions using field maps.
    Note that beyond just in-plane acceleration,
    a variety of other manipulations to the phase encoding need to be accounted
    for properly, including partial fourier, phase oversampling,
    phase resolution, phase field-of-view and interpolation.
  type: number
  exclusiveMinimum: 0
  unit: s
ElectricalStimulation:
  name: ElectricalStimulation
  display_name: Electrical Stimulation
  description: |
    Boolean field to specify if electrical stimulation was done during the
    recording (options are `true` or `false`). Parameters for event-like
    stimulation should be specified in the `events.tsv` file.
  type: boolean
ElectricalStimulationParameters:
  name: ElectricalStimulationParameters
  display_name: Electrical Stimulation Parameters
  description: |
    Free form description of stimulation parameters, such as frequency or shape.
    Specific onsets can be specified in the events.tsv file.
    Specific shapes can be described here in freeform text.
  type: string
ElectrodeManufacturer:
  name: ElectrodeManufacturer
  display_name: Electrode Manufacturer
  description: |
    Can be used if all electrodes are of the same manufacturer
    (for example, `"AD-TECH"`, `"DIXI"`).
    If electrodes of different manufacturers are used,
    please use the corresponding table in the `_electrodes.tsv` file.
  type: string
ElectrodeManufacturersModelName:
  name: ElectrodeManufacturersModelName
  display_name: Electrode Manufacturers Model Name
  description: |
    If different electrode types are used,
    please use the corresponding table in the `_electrodes.tsv` file.
  type: string
EncodingTechnique:
  name: EncodingTechnique
  display_name: Encoding Technique
  description: |
    The encoding technique used during readout.
    For example, `"Cartesian"`, `"EPSI"`, `"Spiral"`,
    or `"Density-weighted concentric ring trajectory"`.
  type: string
EpochLength:
  name: EpochLength
  display_name: Epoch Length
  description: |
    Duration of individual epochs in seconds (for example, `1`)
    in case of epoched data.
    If recording was continuous or discontinuous, leave out the field.
  type: number
  minimum: 0
EstimationAlgorithm:
  name: EstimationAlgorithm
  display_name: Estimation Algorithm
  description: |
    Type of algorithm used to perform fitting
    (for example, `"linear"`, `"non-linear"`, `"LM"` and such).
  type: string
EstimationReference:
  name: EstimationReference
  display_name: Estimation Reference
  description: |
    Reference to the study/studies on which the implementation is based.
  type: string
EthicsApprovals:
  name: EthicsApprovals
  display_name: Ethics Approvals
  description: |
    List of ethics committee approvals of the research protocols and/or
    protocol identifiers.
  type: array
  items:
    type: string
FiducialsCoordinateSystem:
  name: FiducialsCoordinateSystem
  display_name: Fiducials Coordinate System
  description: |
    Defines the coordinate system for the fiducials.
    Preferably the same as the `"EEGCoordinateSystem"`.
    See the
    [Coordinate Systems Appendix](SPEC_ROOT/appendices/coordinate-systems.md)
    for a list of restricted keywords for coordinate systems.
    If `"Other"`, provide definition of the coordinate system in
    `"FiducialsCoordinateSystemDescription"`.
  anyOf:
    - $ref: objects.metadata._MEGCoordSys
    - $ref: objects.metadata._EEGCoordSys
    - $ref: objects.metadata._StandardTemplateCoordSys
    - $ref: objects.metadata._StandardTemplateDeprecatedCoordSys
FiducialsCoordinateSystemDescription:
  name: FiducialsCoordinateSystemDescription
  display_name: Fiducials Coordinate System Description
  description: |
    Free-form text description of the coordinate system.
    May also include a link to a documentation page or paper describing the
    system in greater detail.
  type: string
FiducialsCoordinateUnits:
  name: FiducialsCoordinateUnits
  display_name: Fiducials Coordinate Units
  description: |
    Units in which the coordinates that are  listed in the field
    `"FiducialsCoordinateSystem"` are represented.
  type: string
  enum:
    - m
    - mm
    - cm
    - n/a
FiducialsCoordinates:
  name: FiducialsCoordinates
  display_name: Fiducials Coordinates
  description: |
    Key-value pairs of the labels and 3-D digitized position of anatomical
    landmarks, interpreted following the `"FiducialsCoordinateSystem"`
    (for example, `{"NAS": [12.7,21.3,13.9], "LPA": [5.2,11.3,9.6],
    "RPA": [20.2,11.3,9.1]}`).
    Each array MUST contain three numeric values corresponding to x, y, and z
    axis of the coordinate system in that exact order.
  type: object
  additionalProperties:
    type: array
    items:
      type: number
    minItems: 3
    maxItems: 3
FiducialsDescription:
  name: FiducialsDescription
  display_name: Fiducials Description
  description: |
    Free-form text description of how the fiducials such as vitamin-E capsules
    were placed relative to anatomical landmarks,
    and how the position of the fiducials were measured
    (for example, `"both with Polhemus and with T1w MRI"`).
  type: string
FlipAngle:
  name: FlipAngle
  display_name: Flip Angle
  description: |
    Flip angle (FA) for the acquisition, specified in degrees.
    Corresponds to: DICOM Tag 0018, 1314 `Flip Angle`.
    The data type number may apply to files from any MRI modality concerned with
    a single value for this field, or to the files in a
    [file collection](SPEC_ROOT/appendices/file-collections.md)
    where the value of this field is iterated using the
    [`flip` entity](SPEC_ROOT/appendices/entities.md#flip).
  anyOf:
    - type: number
      unit: degree
      exclusiveMinimum: 0
      maximum: 360
    - type: array
      items:
        type: number
        unit: degree
        exclusiveMinimum: 0
        maximum: 360
FrameDuration:
  name: FrameDuration
  display_name: Frame Duration
  description: |
    Time duration of each frame in default unit seconds.
    This corresponds to DICOM Tag 0018, 1242 `Actual Frame Duration` converted
    to seconds.
  type: array
  items:
    type: number
  unit: s
FrameTimesStart:
  name: FrameTimesStart
  display_name: Frame Times Start
  description: |
    Start times for all frames relative to `"TimeZero"` in default unit seconds.
  type: array
  items:
    type: number
  unit: s
Funding:
  name: Funding
  display_name: Funding
  description: |
    List of sources of funding (grant numbers).
  type: array
  items:
    type: string
GeneratedBy:
  name: GeneratedBy
  display_name: Generated By
  description: |
    Used to specify provenance of the dataset.
  type: array
  minItems: 1
  items:
    type: object
    required_fields: [Name]
    recommended_fields: [Version]
    properties:
      Name:
        name: Name
        description: |
          Name of the pipeline or process that generated the outputs. Use `"Manual"` to
          indicate the derivatives were generated by hand, or adjusted manually after an
          initial run of an automated pipeline.
        type: string
      Version:
        name: Version
        description: Version of the pipeline
        type: string
      Description:
        name: Description
        description: |
          Plain-text description of the pipeline or process that generated the outputs.
          RECOMMENDED if `Name` is `"Manual"`.
        type: string
      CodeURL:
        name: CodeURL
        description: URL where the code used to generate the dataset may be found.
        type: string
        format: uri
      Container:
        name: Container
        description: |
          Used to specify the location and relevant attributes of software container image
          used to produce the dataset. Valid keys in this object include `Type`, `Tag` and
          [`URI`][uri] with [string][] values.
        type: object
        recommended_fields:
          - Type
          - Tag
          - URI
        properties:
          Type:
            type: string
          Tag:
            type: string
          URI:
            type: string
            format: uri
GeneticLevel:
  name: GeneticLevel
  display_name: Genetic Level
  description: |
    Describes the level of analysis.
    Values MUST be one of `"Genetic"`, `"Genomic"`, `"Epigenomic"`,
    `"Transcriptomic"`, `"Metabolomic"`, or `"Proteomic"`.
  anyOf:
    - $ref: objects.metadata._GeneticLevelEnum
    - type: array
      items:
        $ref: objects.metadata._GeneticLevelEnum
Genetics:
  name: Genetics
  display_name: Genetics
  description: |
    An object containing information about the genetics descriptor.
  type: object
  properties:
    Database:
      name: Database
      description: |
        [URI](SPEC_ROOT/common-principles.md#uniform-resource-indicator)
        of database where the dataset is hosted.
      type: string
      format: uri
    Dataset:
      name: Dataset
      description: |
        [URI](SPEC_ROOT/common-principles.md#uniform-resource-indicator)
        where data can be retrieved.
      type: string
      format: uri
    Descriptors:
      name: Descriptors
      description: |
        List of relevant descriptors (for example, journal articles) for dataset
        using a valid
        [URI](SPEC_ROOT/common-principles.md#uniform-resource-indicator)
        when possible.
      anyOf:
        - type: string
        - type: array
          items:
            type: string
GradientSetType:
  name: GradientSetType
  display_name: Gradient Set Type
  description: |
    It should be possible to infer the gradient coil from the scanner model.
    If not, for example because of a custom upgrade or use of a gradient
    insert set, then the specifications of the actual gradient coil should be
    reported independently.
  type: string
GYROChannelCount:
  name: GYROChannelCount
  display_name: Gyrometer Channel Count
  description: |
    Number of gyrometer channels.
  type: integer
  minimum: 0
HED:
  name: HED
  display_name: HED
  description: |
    Hierarchical Event Descriptor (HED) information,
    see the [HED Appendix](SPEC_ROOT/appendices/hed.md) for details.
  anyOf:
    - type: string
    - type: object
      additionalProperties:
        type: string
HEDVersion:
  name: HEDVersion
  display_name: HED Version
  description: |
    If HED tags are used:
    The version of the HED schema used to validate HED tags for study.
    May include a single schema or a base schema and one or more library schema.
  anyOf:
    - type: string
      format: hed_version
    - type: array
      items:
        type: string
        format: hed_version
Haematocrit:
  name: Haematocrit
  display_name: Haematocrit
  description: |
    Measured haematocrit, meaning the volume of erythrocytes divided by the
    volume of whole blood.
  type: number
HardcopyDeviceSoftwareVersion:
  name: HardcopyDeviceSoftwareVersion
  display_name: Hardcopy Device Software Version
  description: |
    Manufacturer's designation of the software of the device that created this
    Hardcopy Image (the printer).
    Corresponds to DICOM Tag 0018, 101A `Hardcopy Device Software Version`.
  type: string
HardwareFilters:
  name: HardwareFilters
  display_name: Hardware Filters
  description: |
    Object of temporal hardware filters applied, or `"n/a"` if the data is not
    available. Each key-value pair in the JSON object is a name of the filter and
    an object in which its parameters are defined as key-value pairs.
    For example, `{"Highpass RC filter": {"Half amplitude cutoff (Hz)":
    0.0159, "Roll-off": "6dB/Octave"}}`.
  anyOf:
    - type: object
      additionalProperties:
        type: object
    - type: string
      enum:
        - n/a
HeadCircumference:
  name: HeadCircumference
  display_name: Head Circumference
  description: |
    Circumference of the participant's head, expressed in cm (for example, `58`).
  type: number
  exclusiveMinimum: 0
  unit: cm
HeadCoilCoordinateSystem:
  name: HeadCoilCoordinateSystem
  display_name: Head Coil Coordinate System
  description: |
    Defines the coordinate system for the head coils.
    See the
    [Coordinate Systems Appendix](SPEC_ROOT/appendices/coordinate-systems.md)
    for a list of restricted keywords for coordinate systems.
    If `"Other"`, provide definition of the coordinate system in
    `HeadCoilCoordinateSystemDescription`.
  anyOf:
    - $ref: objects.metadata._MEGCoordSys
    - $ref: objects.metadata._EEGCoordSys
    - $ref: objects.metadata._StandardTemplateCoordSys
    - $ref: objects.metadata._StandardTemplateDeprecatedCoordSys
HeadCoilCoordinateSystemDescription:
  name: HeadCoilCoordinateSystemDescription
  display_name: Head Coil Coordinate System Description
  description: |
    Free-form text description of the coordinate system.
    May also include a link to a documentation page or paper describing the system in greater detail.
  type: string
HeadCoilCoordinateUnits:
  name: HeadCoilCoordinateUnits
  display_name: Head Coil Coordinate Units
  description: |
    Units of the coordinates of `HeadCoilCoordinateSystem`.
  type: string
  enum:
    - m
    - mm
    - cm
    - n/a
HeadCoilCoordinates:
  name: HeadCoilCoordinates
  display_name: Head Coil Coordinates
  description: |
    Key-value pairs describing head localization coil labels and their
    coordinates, interpreted following the `HeadCoilCoordinateSystem`
    (for example, `{"NAS": [12.7,21.3,13.9], "LPA": [5.2,11.3,9.6],
    "RPA": [20.2,11.3,9.1]}`).
    Note that coils are not always placed at locations that have a known
    anatomical name (for example, for Neuromag/Elekta/MEGIN, Yokogawa systems);
    in that case generic labels can be used
    (for example, `{"coil1": [12.2,21.3,12.3], "coil2": [6.7,12.3,8.6],
    "coil3": [21.9,11.0,8.1]}`).
    Each array MUST contain three numeric values corresponding to x, y, and z
    axis of the coordinate system in that exact order.
  type: object
  additionalProperties:
    type: array
    items:
      type: number
    minItems: 3
    maxItems: 3
HeadCoilFrequency:
  name: HeadCoilFrequency
  display_name: Head Coil Frequency
  description: |
    List of frequencies (in Hz) used by the head localisation coils
    ('HLC' in CTF systems, 'HPI' in Neuromag/Elekta/MEGIN, 'COH' in BTi/4D)
    that track the subject's head position in the MEG helmet
    (for example, `[293, 307, 314, 321]`).
  anyOf:
    - type: number
      unit: Hz
    - type: array
      items:
        type: number
        unit: Hz
HowToAcknowledge:
  name: HowToAcknowledge
  display_name: How To Acknowledge
  description: |
    Text containing instructions on how researchers using this dataset should
    acknowledge the original authors.
    This field can also be used to define a publication that should be cited in
    publications that use the dataset.
  type: string
ImageAcquisitionProtocol:
  name: ImageAcquisitionProtocol
  display_name: Image Acquisition Protocol
  description: |
    Description of the image acquisition protocol or
    [URI](SPEC_ROOT/common-principles.md#uniform-resource-indicator)
    (for example from [protocols.io](https://www.protocols.io/)).
  type: string
ImageDecayCorrected:
  name: ImageDecayCorrected
  display_name: Image Decay Corrected
  description: |
    Boolean flag specifying whether the image data have been decay-corrected.
  type: boolean
ImageDecayCorrectionTime:
  name: ImageDecayCorrectionTime
  display_name: Image Decay Correction Time
  description: |
    Point in time from which the decay correction was applied with respect to
    `"TimeZero"` in the default unit seconds.
  type: number
  unit: s
Immersion:
  name: Immersion
  display_name: Immersion
  description: |
    Lens immersion medium. If the file format is OME-TIFF, the value MUST be consistent
    with the `Immersion` OME metadata field.
  type: string
InfusionRadioactivity:
  name: InfusionRadioactivity
  display_name: Infusion Radioactivity
  description: |
    Amount of radioactivity infused into the patient.
    This value must be less than or equal to the total injected radioactivity
    (`"InjectedRadioactivity"`).
    Units should be the same as `"InjectedRadioactivityUnits"`.
  type: number
InfusionSpeed:
  name: InfusionSpeed
  display_name: Infusion Speed
  description: |
    If given, infusion speed.
  type: number
InfusionSpeedUnits:
  name: InfusionSpeedUnits
  display_name: Infusion Speed Units
  description: |
    Unit of infusion speed (for example, `"mL/s"`).
  type: string
  format: unit
InfusionStart:
  name: InfusionStart
  display_name: Infusion Start
  description: |
    Time of start of infusion with respect to `"TimeZero"` in the default unit
    seconds.
  type: number
  unit: s
InjectedMass:
  name: InjectedMass
  display_name: Injected Mass
  description: |
    Total mass of radiolabeled compound injected into subject (for example, `10`).
    This can be derived as the ratio of the `"InjectedRadioactivity"` and
    `"MolarRadioactivity"`.
    **For those tracers in which injected mass is not available (for example FDG)
    can be set to `"n/a"`)**.
  anyOf:
    - type: number
    - type: string
      enum:
        - n/a
InjectedMassPerWeight:
  name: InjectedMassPerWeight
  display_name: Injected Mass Per Weight
  description: |
    Injected mass per kilogram bodyweight.
  type: number
InjectedMassPerWeightUnits:
  name: InjectedMassPerWeightUnits
  display_name: Injected Mass Per Weight Units
  description: |
    Unit format of the injected mass per kilogram bodyweight
    (for example, `"ug/kg"`).
  type: string
  format: unit
InjectedMassUnits:
  name: InjectedMassUnits
  display_name: Injected Mass Units
  description: |
    Unit format of the mass of compound injected (for example, `"ug"` or
    `"umol"`).
    **Note this is not required for an FDG acquisition, since it is not available,
    and SHOULD be set to `"n/a"`**.
  anyOf:
    - type: string
      format: unit
    - type: string
      enum:
        - n/a
InjectedRadioactivity:
  name: InjectedRadioactivity
  display_name: Injected Radioactivity
  description: |
    Total amount of radioactivity injected into the patient (for example, `400`).
    For bolus-infusion experiments, this value should be the sum of all injected
    radioactivity originating from both bolus and infusion.
    Corresponds to DICOM Tag 0018, 1074 `Radionuclide Total Dose`.
  type: number
InjectedRadioactivityUnits:
  name: InjectedRadioactivityUnits
  display_name: Injected Radioactivity Units
  description: |
    Unit format of the specified injected radioactivity (for example, `"MBq"`).
  type: string
  format: unit
InjectedVolume:
  name: InjectedVolume
  display_name: Injected Volume
  description: |
    Injected volume of the radiotracer in the unit `"mL"`.
  type: number
  unit: mL
InjectionEnd:
  name: InjectionEnd
  display_name: Injection End
  description: |
    Time of end of injection with respect to `"TimeZero"` in the default unit
    seconds.
  type: number
  unit: s
InjectionStart:
  name: InjectionStart
  display_name: Injection Start
  description: |
    Time of start of injection with respect to `"TimeZero"` in the default unit
    seconds.
    This corresponds to DICOM Tag 0018, 1072 `Contrast/Bolus Start Time`
    converted to seconds relative to `"TimeZero"`.
  type: number
  unit: s
InstitutionAddress:
  name: InstitutionAddress
  display_name: Institution Address
  description: |
    The address of the institution in charge of the equipment that produced the
    measurements.
  type: string
InstitutionName:
  name: InstitutionName
  display_name: Institution Name
  description: |
    The name of the institution in charge of the equipment that produced the
    measurements.
  type: string
InstitutionalDepartmentName:
  name: InstitutionalDepartmentName
  display_name: Institutional Department Name
  description: |
    The department in the institution in charge of the equipment that produced
    the measurements.
  type: string
Instructions:
  name: Instructions
  display_name: Instructions
  description: |
    Text of the instructions given to participants before the recording.
  type: string
IntendedFor:
  name: IntendedFor
  display_name: Intended For
  description: |
    The paths to files for which the associated file is intended to be used.
    Contains one or more [BIDS URIs](SPEC_ROOT/common-principles.md#bids-uri).
    Using forward-slash separated paths relative to the participant subdirectory is
    [DEPRECATED](SPEC_ROOT/common-principles.md#definitions).
  anyOf:
    - type: string
      format: bids_uri
    - type: string
      format: participant_relative
    - type: array
      items:
        anyOf:
          - type: string
            format: bids_uri
          - type: string
            format: participant_relative
IntendedFor__ds_relative:
  name: IntendedFor
  display_name: Intended For
  description: |
    The paths to files for which the associated file is intended to be used.
    Contains one or more [BIDS URIs](SPEC_ROOT/common-principles.md#bids-uri).
    Using forward-slash separated paths relative to the dataset root is
    [DEPRECATED](SPEC_ROOT/common-principles.md#definitions).
  anyOf:
    - type: string
      format: bids_uri
    - type: string
      format: dataset_relative
    - type: array
      items:
        anyOf:
          - type: string
            format: bids_uri
          - type: string
            format: dataset_relative
InversionTime:
  name: InversionTime
  display_name: Inversion Time
  description: |
    The inversion time (TI) for the acquisition, specified in seconds.
    Inversion time is the time after the middle of inverting RF pulse to middle
    of excitation pulse to detect the amount of longitudinal magnetization.
    Corresponds to DICOM Tag 0018, 0082 `Inversion Time`
    (please note that the DICOM term is in milliseconds not seconds).
  type: number
  unit: s
  exclusiveMinimum: 0
LabelingDistance:
  name: LabelingDistance
  display_name: Labeling Distance
  description: |
    Distance from the center of the imaging slab to the center of the labeling
    plane (`(P)CASL`) or the leading edge of the labeling slab (`PASL`),
    in millimeters.
    If the labeling is performed inferior to the isocenter,
    this number should be negative.
    Based on DICOM macro C.8.13.5.14.
  type: number
  unit: mm
LabelingDuration:
  name: LabelingDuration
  display_name: Labeling Duration
  description: |
    Total duration of the labeling pulse train, in seconds,
    corresponding to the temporal width of the labeling bolus for
    `"PCASL"` or `"CASL"`.
    In case all control-label volumes (or deltam or CBF) have the same
    `LabelingDuration`, a scalar must be specified.
    In case the control-label volumes (or deltam or cbf) have a different
    `"LabelingDuration"`, an array of numbers must be specified,
    for which any `m0scan` in the timeseries has a `"LabelingDuration"` of zero.
    In case an array of numbers is provided,
    its length should be equal to the number of volumes specified in
    `*_aslcontext.tsv`.
    Corresponds to DICOM Tag 0018, 9258 `ASL Pulse Train Duration`.
  anyOf:
    - type: number
      minimum: 0
      unit: s
    - type: array
      items:
        type: number
        unit: s
        minimum: 0
LabelingEfficiency:
  name: LabelingEfficiency
  display_name: Labeling Efficiency
  description: |
    Labeling efficiency, specified as a number between zero and one,
    only if obtained externally (for example phase-contrast based).
  type: number
  exclusiveMinimum: 0
LabelingLocationDescription:
  name: LabelingLocationDescription
  display_name: Labeling Location Description
  description: |
    Description of the location of the labeling plane (`"CASL"` or `"PCASL"`) or
    the labeling slab (`"PASL"`) that cannot be captured by fields
    `LabelingOrientation` or `LabelingDistance`.
    May include a link to an anonymized screenshot of the planning of the
    labeling slab/plane with respect to the imaging slab or slices
    `*_asllabeling.jpg`.
    Based on DICOM macro C.8.13.5.14.
  type: string
LabelingOrientation:
  name: LabelingOrientation
  display_name: Labeling Orientation
  description: |
    Orientation of the labeling plane (`(P)CASL`) or slab (`PASL`).
    The direction cosines of a normal vector perpendicular to the ASL labeling
    slab or plane with respect to the patient.
    Corresponds to DICOM Tag 0018, 9255 `ASL Slab Orientation`.
  type: array
  items:
    type: number
LabelingPulseAverageB1:
  name: LabelingPulseAverageB1
  display_name: Labeling Pulse Average B1
  description: |
    The average B1-field strength of the RF labeling pulses, in microteslas.
    As an alternative, `"LabelingPulseFlipAngle"` can be provided.
  type: number
  exclusiveMinimum: 0
  unit: uT
LabelingPulseAverageGradient:
  name: LabelingPulseAverageGradient
  display_name: Labeling Pulse Average Gradient
  description: |
    The average labeling gradient, in milliteslas per meter.
  type: number
  exclusiveMinimum: 0
  unit: mT/m
LabelingPulseDuration:
  name: LabelingPulseDuration
  display_name: Labeling Pulse Duration
  description: |
    Duration of the individual labeling pulses, in milliseconds.
  type: number
  exclusiveMinimum: 0
  unit: ms
LabelingPulseFlipAngle:
  name: LabelingPulseFlipAngle
  display_name: Labeling Pulse Flip Angle
  description: |
    The flip angle of a single labeling pulse, in degrees,
    which can be given as an alternative to `"LabelingPulseAverageB1"`.
  type: number
  exclusiveMinimum: 0
  maximum: 360
  unit: degree
LabelingPulseInterval:
  name: LabelingPulseInterval
  display_name: Labeling Pulse Interval
  description: |
    Delay between the peaks of the individual labeling pulses, in milliseconds.
  type: number
  exclusiveMinimum: 0
  unit: ms
LabelingPulseMaximumGradient:
  name: LabelingPulseMaximumGradient
  display_name: Labeling Pulse Maximum Gradient
  description: |
    The maximum amplitude of the gradient switched on during the application of
    the labeling RF pulse(s), in milliteslas per meter.
  type: number
  exclusiveMinimum: 0
  unit: mT/m
LabelingSlabThickness:
  name: LabelingSlabThickness
  display_name: Labeling Slab Thickness
  description: |
    Thickness of the labeling slab in millimeters.
    For non-selective FAIR a zero is entered.
    Corresponds to DICOM Tag 0018, 9254 `ASL Slab Thickness`.
  type: number
  exclusiveMinimum: 0
  unit: mm
Levels:
  name: Levels
  display_name: Levels
  description: |
    For categorical variables: An object of possible values (keys) and their
    descriptions (values).
  type: object
  additionalProperties:
    type: string
License:
  name: License
  display_name: License
  description: |
    The license for the dataset.
    The use of license name abbreviations is RECOMMENDED for specifying a license
    (see [Licenses](SPEC_ROOT/appendices/licenses.md)).
    The corresponding full license text MAY be specified in an additional
    `LICENSE` file.
  type: string
LongName:
  name: LongName
  display_name: Long Name
  description: |
    Long (unabbreviated) name of the column.
  type: string
LookLocker:
  name: LookLocker
  display_name: Look Locker
  description: |
    Boolean indicating if a Look-Locker readout is used.
  type: boolean
M0Estimate:
  name: M0Estimate
  display_name: M0Estimate
  description: |
    A single numerical whole-brain M0 value (referring to the M0 of blood),
    only if obtained externally
    (for example retrieved from CSF in a separate measurement).
  type: number
  exclusiveMinimum: 0
M0Type:
  name: M0Type
  display_name: M0Type
  description: |
    Describes the presence of M0 information.
    `"Separate"` means that a separate `*_m0scan.nii[.gz]` is present.
    `"Included"` means that an m0scan volume is contained within the current
    `*_asl.nii[.gz]`.
    `"Estimate"` means that a single whole-brain M0 value is provided.
    `"Absent"` means that no specific M0 information is present.
  type: string
  enum:
    - Separate
    - Included
    - Estimate
    - Absent
MAGNChannelCount:
  name: MAGNChannelCount
  display_name: Magnetometer Channel Count
  description: |
    Number of magnetometer channels.
  type: integer
  minimum: 0
MEGChannelCount:
  name: MEGChannelCount
  display_name: MEG Channel Count
  description: |
    Number of MEG channels (for example, `275`).
  type: integer
  minimum: 0
MEGCoordinateSystem:
  name: MEGCoordinateSystem
  display_name: MEG Coordinate System
  description: |
    Defines the coordinate system for the MEG sensors.
    See the
    [Coordinate Systems Appendix](SPEC_ROOT/appendices/coordinate-systems.md)
    for a list of restricted keywords for coordinate systems.
    If `"Other"`, provide definition of the coordinate system in
    `"MEGCoordinateSystemDescription"`.
  anyOf:
    - $ref: objects.metadata._MEGCoordSys
    - $ref: objects.metadata._EEGCoordSys
    - $ref: objects.metadata._StandardTemplateCoordSys
    - $ref: objects.metadata._StandardTemplateDeprecatedCoordSys
MEGCoordinateSystemDescription:
  name: MEGCoordinateSystemDescription
  display_name: MEG Coordinate System Description
  description: |
    Free-form text description of the coordinate system.
    May also include a link to a documentation page or paper describing the
    system in greater detail.
  type: string
MEGCoordinateUnits:
  name: MEGCoordinateUnits
  display_name: MEG Coordinate Units
  description: |
    Units of the coordinates of `"MEGCoordinateSystem"`.
  type: string
  enum:
    - m
    - mm
    - cm
    - n/a
MEGREFChannelCount:
  name: MEGREFChannelCount
  display_name: MEGREF Channel Count
  description: |
    Number of MEG reference channels (for example, `23`).
    For systems without such channels (for example, Neuromag Vectorview),
    `MEGREFChannelCount` should be set to `0`.
  type: integer
  minimum: 0
MRAcquisitionType:
  name: MRAcquisitionType
  display_name: MR Acquisition Type
  description: |
    Type of sequence readout.
    Corresponds to DICOM Tag 0018, 0023 `MR Acquisition Type`.
  type: string
  enum:
    - 2D
    - 3D
MRAcquisitionType__mrs:
  name: MRAcquisitionType
  display_name: MR Acquisition Type
  description: |
    Type of sequence readout.
  type: string
  enum:
    - 1D
    - 2D
    - 3D
MRTransmitCoilSequence:
  name: MRTransmitCoilSequence
  display_name: MR Transmit Coil Sequence
  description: |
    This is a relevant field if a non-standard transmit coil is used.
    Corresponds to DICOM Tag 0018, 9049 `MR Transmit Coil Sequence`.
  type: string
MTNumberOfPulses:
  name: MTNumberOfPulses
  display_name: MT Number Of Pulses
  description: |
    The number of magnetization transfer RF pulses applied before the readout.
  type: number
MTOffsetFrequency:
  name: MTOffsetFrequency
  display_name: MT Offset Frequency
  description: |
    The frequency offset of the magnetization transfer pulse with respect to the
    central H1 Larmor frequency in Hertz (Hz).
  type: number
  unit: Hz
MTPulseBandwidth:
  name: MTPulseBandwidth
  display_name: MT Pulse Bandwidth
  description: |
    The excitation bandwidth of the magnetization transfer pulse in Hertz (Hz).
  type: number
  unit: Hz
MTPulseDuration:
  name: MTPulseDuration
  display_name: MT Pulse Duration
  description: |
    Duration of the magnetization transfer RF pulse in seconds.
  type: number
  unit: s
MTPulseShape:
  name: MTPulseShape
  display_name: MT Pulse Shape
  description: |
    Shape of the magnetization transfer RF pulse waveform.
    The value `"GAUSSHANN"` refers to a Gaussian pulse with a Hanning window.
    The value `"SINCHANN"` refers to a sinc pulse with a Hanning window.
    The value `"SINCGAUSS"` refers to a sinc pulse with a Gaussian window.
  type: string
  enum:
    - HARD
    - GAUSSIAN
    - GAUSSHANN
    - SINC
    - SINCHANN
    - SINCGAUSS
    - FERMI
MTState:
  name: MTState
  display_name: MT State
  description: |
    Boolean stating whether the magnetization transfer pulse is applied.
    Corresponds to DICOM Tag 0018, 9020 `Magnetization Transfer`.
  type: boolean
MagneticFieldStrength:
  name: MagneticFieldStrength
  display_name: Magnetic Field Strength
  description: |
    Nominal field strength of MR magnet in Tesla.
    Corresponds to DICOM Tag 0018, 0087 `Magnetic Field Strength`.
  type: number
Magnification:
  name: Magnification
  display_name: Magnification
  description: |
    Lens magnification (for example: `40`). If the file format is OME-TIFF,
    the value MUST be consistent with the `"NominalMagnification"` OME metadata field.
  type: number
  exclusiveMinimum: 0
Manual:
  name: Manual
  display_name: Manual
  description: |
    Indicates if the segmentation was performed manually or via an automated
    process.
  type: boolean
Manufacturer:
  name: Manufacturer
  display_name: Manufacturer
  description: |
    Manufacturer of the equipment that produced the measurements.
  type: string
ManufacturersModelName:
  name: ManufacturersModelName
  display_name: Manufacturers Model Name
  description: |
    Manufacturer's model name of the equipment that produced the measurements.
  type: string
MatrixCoilMode:
  name: MatrixCoilMode
  display_name: Matrix Coil Mode
  description: |
    (If used)
    A method for reducing the number of independent channels by combining in
    analog the signals from multiple coil elements.
    There are typically different default modes when using un-accelerated or
    accelerated (for example, `"GRAPPA"`, `"SENSE"`) imaging.
  type: string
MatrixSize:
  name: MatrixSize
  display_name: Matrix Size
  description: |
    An array of integers with a length of 3 denoting the matrix size of the acquisition slab.
    This should be specified as, for example, `[32, 32, 1]` for a 2D acquisition
    or `[32, 1, 1]` for a 1D acquisition.
  type: array
  minItems: 3
  maxItems: 3
  items:
    type: integer
    exclusiveMinimum: 1
MaxMovement:
  name: MaxMovement
  display_name: Max Movement
  description: |
    Maximum head movement (in mm) detected during the recording,
    as measured by the head localisation coils (for example, `4.8`).
  type: number
  unit: mm
MeasurementToolMetadata:
  name: MeasurementToolMetadata
  display_name: Measurement Tool Metadata
  description: |
    A description of the measurement tool as a whole.
    Contains two fields: `"Description"` and `"TermURL"`.
    `"Description"` is a free text description of the measurement tool.
    `"TermURL"` is a URL to an entity in an ontology corresponding to this tool.
  type: object
  properties:
    TermURL:
      type: string
      format: uri
    Description:
      type: string
MetaboliteAvail:
  name: MetaboliteAvail
  display_name: Metabolite Available
  description: |
    Boolean that specifies if metabolite measurements are available.
    If `true`, the `metabolite_parent_fraction` column MUST be present in the
    corresponding `*_blood.tsv` file.
  type: boolean
MetaboliteMethod:
  name: MetaboliteMethod
  display_name: Metabolite Method
  description: |
    Method used to measure metabolites.
  type: string
MetaboliteRecoveryCorrectionApplied:
  name: MetaboliteRecoveryCorrectionApplied
  display_name: Metabolite Recovery Correction Applied
  description: |
    Metabolite recovery correction from the HPLC, for tracers where it changes
    with time postinjection.
    If `true`, the `hplc_recovery_fractions` column MUST be present in the
    corresponding `*_blood.tsv` file.
  type: boolean
MiscChannelCount:
  name: MiscChannelCount
  display_name: Misc Channel Count
  description: |
    Number of miscellaneous analog channels for auxiliary signals.
  type: integer
  minimum: 0
MixingTime:
  name: MixingTime
  display_name: Mixing Time
  description: |
    In the context of a stimulated- and spin-echo 3D EPI sequence for B1+ mapping
    or a stimulated-echo MRS sequence,
    corresponds to the interval between spin- and stimulated-echo pulses.
    In the context of a diffusion-weighted double spin-echo sequence,
    corresponds to the interval between two successive diffusion sensitizing
    gradients, specified in seconds.
  type: number
  unit: s
ModeOfAdministration:
  name: ModeOfAdministration
  display_name: Mode Of Administration
  description: |
    Mode of administration of the injection
    (for example, `"bolus"`, `"infusion"`, or `"bolus-infusion"`).
  type: string
MolarActivity:
  name: MolarActivity
  display_name: Molar Activity
  description: |
    Molar activity of compound injected.
    Corresponds to DICOM Tag 0018, 1077 `Radiopharmaceutical Specific Activity`.
  type: number
MolarActivityMeasTime:
  name: MolarActivityMeasTime
  display_name: Molar Activity Measurement Time
  description: |
    Time to which molar radioactivity measurement above applies in the default
    unit `"hh:mm:ss"`.
  type: string
  format: time
MolarActivityUnits:
  name: MolarActivityUnits
  display_name: Molar Activity Units
  description: |
    Unit of the specified molar radioactivity (for example, `"GBq/umol"`).
  type: string
  format: unit
MultibandAccelerationFactor:
  name: MultibandAccelerationFactor
  display_name: Multiband Acceleration Factor
  description: |
    The multiband factor, for multiband acquisitions.
  type: number
MultipartID:
  name: MultipartID
  display_name: MultipartID
  description: |
    A unique (per participant) label tagging DWI runs that are part of a
    multipart scan.
  type: string
Name:
  name: Name
  display_name: Name
  description: |
    Name of the dataset.
  type: string
NegativeContrast:
  name: NegativeContrast
  display_name: Negative Contrast
  description: |
    `true` or `false` value specifying whether increasing voxel intensity
    (within sample voxels) denotes a decreased value with respect to the
    contrast suffix.
    This is commonly the case when Cerebral Blood Volume is estimated via
    usage of a contrast agent in conjunction with a T2\* weighted acquisition
    protocol.
  type: boolean
NIRSChannelCount:
  name: NIRSChannelCount
  display_name: NIRS Channel Count
  description: |
    Total number of NIRS channels, including short channels.
    Corresponds to the number of rows in `channels.tsv` with any NIRS type.
  type: integer
  minimum: 0
NIRSSourceOptodeCount:
  name: NIRSSourceOptodeCount
  display_name: NIRS Source Optode Count
  description: |
    Number of NIRS sources.
    Corresponds to the number of rows in `optodes.tsv` with type `"source"`.
  type: integer
  minimum: 1
NIRSDetectorOptodeCount:
  name: NIRSDetectorOptodeCount
  display_name: NIRS Detector Optode Channel Count
  description: |
    Number of NIRS detectors.
    Corresponds to the number of rows in `optodes.tsv` with type `"detector"`.
  type: integer
  minimum: 1
NIRSPlacementScheme:
  name: NIRSPlacementScheme
  display_name: NIRS Placement Scheme
  description: |
    Placement scheme of NIRS optodes.
    Either the name of a standardized placement system (for example, `"10-20"`)
    or an array of standardized position names (for example, `["Cz", "Pz"]`).
    This field should only be used if a cap was not used.
    If a standard cap was used, then it should be specified in `CapManufacturer`
    and `CapManufacturersModelName` and this field should be set to `"n/a"`
  anyOf:
    - type: string
    - type: array
      items:
        type: string
NIRSCoordinateSystem:
  name: NIRSCoordinateSystem
  display_name: NIRS Coordinate System
  description: |
    Defines the coordinate system in which the optode positions are expressed.

    See
    [Appendix VIII](SPEC_ROOT/appendices/coordinate-systems.md)
    for a list of restricted keywords for coordinate systems.
    If `"Other"`, a definition of the coordinate system MUST be
    provided in `NIRSCoordinateSystemDescription`.
  anyOf:
    - $ref: objects.metadata._MEGCoordSys
    - $ref: objects.metadata._EEGCoordSys
    - $ref: objects.metadata._StandardTemplateCoordSys
    - $ref: objects.metadata._StandardTemplateDeprecatedCoordSys
NIRSCoordinateSystemDescription:
  name: NIRSCoordinateSystemDescription
  display_name: NIRS Coordinate System Description
  description: |
    Free-form text description of the coordinate system.
    May also include a link to a documentation page or paper describing the
    system in greater detail.
  type: string
NIRSCoordinateUnits:
  name: NIRSCoordinateUnits
  display_name: NIRS Coordinate Units
  description: |
    Units of the coordinates of `NIRSCoordinateSystem`.
  type: string
  enum:
    - m
    - mm
    - cm
    - n/a
NIRSCoordinateProcessingDescription:
  name: NIRSCoordinateProcessingDescription
  display_name: NIRS Coordinate Processing Description
  description: |
    Has any post-processing (such as projection) been done on the optode
    positions (for example, `"surface_projection"`, `"n/a"`).
  type: string
NonlinearGradientCorrection:
  name: NonlinearGradientCorrection
  display_name: Nonlinear Gradient Correction
  description: |
    Boolean stating if the image saved has been corrected for gradient
    nonlinearities by the scanner sequence.
  type: boolean
NumberOfSpectralPoints:
  name: NumberOfSpectralPoints
  display_name: Number Of Spectral Points
  description: |
    The number of complex data points in each recorded transient of the detected time-domain MR
    signal, equivalent to the number of points in a single spectrum.
  type: integer
NumberOfTransients:
  name: NumberOfTransients
  display_name: Number Of Transients
  description: |
    The number of single applications of the pulse sequence recorded during an MRS acquisiton.
  type: integer
NumberOfVolumesDiscardedByScanner:
  name: NumberOfVolumesDiscardedByScanner
  display_name: Number Of Volumes Discarded By Scanner
  description: |
    Number of volumes ("dummy scans") discarded by the scanner
    (as opposed to those discarded by the user post hoc)
    before saving the imaging file.
    For example, a sequence that automatically discards the first 4 volumes
    before saving would have this field as 4.
    A sequence that does not discard dummy scans would have this set to 0.
    Please note that the onsets recorded in the `events.tsv` file should always
    refer to the beginning of the acquisition of the first volume in the
    corresponding imaging file - independent of the value of
    `"NumberOfVolumesDiscardedByScanner"` field.
  type: integer
  minimum: 0
NumberOfVolumesDiscardedByUser:
  name: NumberOfVolumesDiscardedByUser
  display_name: Number Of Volumes Discarded By User
  description: |
    Number of volumes ("dummy scans") discarded by the user before including the
    file in the dataset.
    If possible, including all of the volumes is strongly recommended.
    Please note that the onsets recorded in the `events.tsv` file should always
    refer to the beginning of the acquisition of the first volume in the
    corresponding imaging file - independent of the value of
    `"NumberOfVolumesDiscardedByUser"` field.
  type: integer
  minimum: 0
NumberReceiveCoilActiveElements:
  name: NumberReceiveCoilActiveElements
  display_name: Number of Receive Coil Active Elements
  description: |
    The number of active RF elements used by the receive coil.
  type: integer
NumberShots:
  name: NumberShots
  display_name: Number Shots
  description: |
    The number of RF excitations needed to reconstruct a slice or volume
    (may be referred to as partition).
    Please mind that this is not the same as Echo Train Length which denotes the
    number of k-space lines collected after excitation in a multi-echo readout.
    The data type array is applicable for specifying this parameter before and
    after the k-space center is sampled.
    Please see
    [`"NumberShots"` metadata field]\
    (SPEC_ROOT/appendices/qmri.md#numbershots-metadata-field)
    in the qMRI appendix for corresponding calculations.
  anyOf:
    - type: number
    - type: array
      items:
        type: number
NumberTransmitCoilActiveElements:
  name: NumberTransmitCoilActiveElements
  display_name: Number of Transmit Coil Active Elements
  description: |
    The number of active RF elements used by the transmit coil.
  type: integer
NumericalAperture:
  name: NumericalAperture
  display_name: Numerical Aperture
  description: |
    Lens numerical aperture (for example: `1.4`). If the file format is OME-TIFF,
    the value MUST be consistent with the `LensNA` OME metadata field.
  type: number
  exclusiveMinimum: 0
OperatingSystem:
  name: OperatingSystem
  display_name: Operating System
  description: |
    Operating system used to run the stimuli presentation software
    (for formatting recommendations, see examples below this table).
  type: string
OtherAcquisitionParameters:
  name: OtherAcquisitionParameters
  display_name: Other Acquisition Parameters
  description: |
    Description of other relevant image acquisition parameters.
  type: string
OuterVolumeSuppression:
  name: OuterVolumeSuppression
  display_name: Other-Volume Suppression
  description: |
    Boolean indicating whether outer-volume suppression was used prior to acquisition.
  type: boolean
PASLType:
  name: PASLType
  display_name: PASL Type
  description: |
    Type of the labeling pulse of the `PASL` labeling,
    for example `"FAIR"`, `"EPISTAR"`, or `"PICORE"`.
  type: string
PCASLType:
  name: PCASLType
  display_name: PCASL Type
  description: |
    The type of gradient pulses used in the `control` condition.
  type: string
  enum:
    - balanced
    - unbalanced
ParallelAcquisitionTechnique:
  name: ParallelAcquisitionTechnique
  display_name: Parallel Acquisition Technique
  description: |
    The type of parallel imaging used (for example `"GRAPPA"`, `"SENSE"`).
    Corresponds to DICOM Tag 0018, 9078 `Parallel Acquisition Technique`.
  type: string
ParallelReductionFactorInPlane:
  name: ParallelReductionFactorInPlane
  display_name: Parallel Reduction Factor In Plane
  description: |
    The parallel imaging (for instance, GRAPPA) factor in plane.
    Use the denominator of the fraction of k-space encoded for each slice.
    For example, 2 means half of k-space is encoded.
    Corresponds to DICOM Tag 0018, 9069 `Parallel Reduction Factor In-plane`.
  type: number
ParallelReductionFactorOutOfPlane:
  name: ParallelReductionFactorOutOfPlane
  display_name: Parallel Reduction Factor Out of Plane
  description: |
    The parallel imaging (for instance, GRAPPA) factor in the second phase encoding dimension of 3D sequences.
    Use the denominator of the fraction of k-space encoded in the second phase encoding dimension.
    For example, 2 means half of k-space is encoded.
    Will typically be 1 for 2D sequences, as each slice in a 2D acquisition is usually fully encoded.
    `ParallelReductionFactorOutOfPlane` should not be confused with `MultibandAccelerationFactor`,
    as they imply different methods of accelerating the acquisition.
    Corresponds to DICOM Tag 0018, 9155 `Parallel Reduction Factor out-of-plane`.
  type: number
PartialFourier:
  name: PartialFourier
  display_name: Partial Fourier
  description: |
    The fraction of partial Fourier information collected.
    Corresponds to DICOM Tag 0018, 9081 `Partial Fourier`.
  type: number
PartialFourierDirection:
  name: PartialFourierDirection
  display_name: Partial Fourier Direction
  description: |
    The direction where only partial Fourier information was collected.
    Corresponds to DICOM Tag 0018, 9036 `Partial Fourier Direction`.
  type: string
PharmaceuticalDoseAmount:
  name: PharmaceuticalDoseAmount
  display_name: Pharmaceutical Dose Amount
  description: |
    Dose amount of pharmaceutical coadministered with tracer.
  anyOf:
    - type: number
    - type: array
      items:
        type: number
PharmaceuticalDoseRegimen:
  name: PharmaceuticalDoseRegimen
  display_name: Pharmaceutical Dose Regimen
  description: |
    Details of the pharmaceutical dose regimen.
    Either adequate description or short-code relating to regimen documented
    elsewhere (for example, `"single oral bolus"`).
  type: string
PharmaceuticalDoseTime:
  name: PharmaceuticalDoseTime
  display_name: Pharmaceutical Dose Time
  description: |
    Time of administration of pharmaceutical dose, relative to time zero.
    For an infusion, this should be a vector with two elements specifying the
    start and end of the infusion period. For more complex dose regimens,
    the regimen description should be complete enough to enable unambiguous
    interpretation of `"PharmaceuticalDoseTime"`.
    Unit format of the specified pharmaceutical dose time MUST be seconds.
  anyOf:
    - type: number
      unit: s
    - type: array
      items:
        type: number
        unit: s
PharmaceuticalDoseUnits:
  name: PharmaceuticalDoseUnits
  display_name: Pharmaceutical Dose Units
  description: |
    Unit format relating to pharmaceutical dose
    (for example, `"mg"` or `"mg/kg"`).
  type: string
  format: unit
PharmaceuticalName:
  name: PharmaceuticalName
  display_name: Pharmaceutical Name
  description: |
    Name of pharmaceutical coadministered with tracer.
  type: string
PhaseEncodingDirection:
  name: PhaseEncodingDirection
  display_name: Phase Encoding Direction
  description: |
    The letters `i`, `j`, `k` correspond to the first, second and third axis of
    the data in the NIFTI file.
    The polarity of the phase encoding is assumed to go from zero index to
    maximum index unless `-` sign is present
    (then the order is reversed - starting from the highest index instead of
    zero).
    `PhaseEncodingDirection` is defined as the direction along which phase is was
    modulated which may result in visible distortions.
    Note that this is not the same as the DICOM term
    `InPlanePhaseEncodingDirection` which can have `ROW` or `COL` values.
  type: string
  enum:
    - i
    - j
    - k
    - i-
    - j-
    - k-
PhotoDescription:
  name: PhotoDescription
  display_name: Photo Description
  description: |
    Description of the photo.
  type: string
PixelSize:
  name: PixelSize
  display_name: Pixel Size
  description: |
    A 2- or 3-number array of the physical size of a pixel, either `[PixelSizeX, PixelSizeY]`
    or `[PixelSizeX, PixelSizeY, PixelSizeZ]`, where X is the width, Y the height and Z the
    depth.
    If the file format is OME-TIFF, these values need to be consistent with `PhysicalSizeX`,
    `PhysicalSizeY` and `PhysicalSizeZ` OME metadata fields, after converting in
    `PixelSizeUnits` according to `PhysicalSizeXunit`, `PhysicalSizeYunit` and
    `PhysicalSizeZunit` OME fields.
  type: array
  minItems: 2
  maxItems: 3
  items:
    type: number
    minimum: 0
PixelSizeUnits:
  name: PixelSizeUnits
  display_name: Pixel Size Units
  description: |
    Unit format of the specified `"PixelSize"`. MUST be one of: `"mm"` (millimeter), `"um"`
    (micrometer) or `"nm"` (nanometer).
  type: string
  enum:
    - mm
    - um
    - nm
PlasmaAvail:
  name: PlasmaAvail
  display_name: Plasma Avail
  description: |
    Boolean that specifies if plasma measurements are available.
  type: boolean
PlasmaFreeFraction:
  name: PlasmaFreeFraction
  display_name: Plasma Free Fraction
  description: |
    Measured free fraction in plasma, meaning the concentration of free compound
    in plasma divided by total concentration of compound in plasma
    (Units: 0-100%).
  type: number
  minimum: 0
  maximum: 100
PlasmaFreeFractionMethod:
  name: PlasmaFreeFractionMethod
  display_name: Plasma Free Fraction Method
  description: |
    Method used to estimate free fraction.
  type: string
PostLabelingDelay:
  name: PostLabelingDelay
  display_name: Post Labeling Delay
  description: |
    This is the postlabeling delay (PLD) time, in seconds, after the end of the
    labeling (for `"CASL"` or `"PCASL"`) or middle of the labeling pulse
    (for `"PASL"`) until the middle of the excitation pulse applied to the
    imaging slab (for 3D acquisition) or first slice (for 2D acquisition).
    Can be a number (for a single-PLD time series) or an array of numbers
    (for multi-PLD and Look-Locker).
    In the latter case, the array of numbers contains the PLD of each volume,
    namely each `control` and `label`, in the acquisition order.
    Any image within the time-series without a PLD, for example an `m0scan`,
    is indicated by a zero.
    Based on DICOM Tags 0018, 9079 `Inversion Times` and 0018, 0082
    `InversionTime`.
  anyOf:
    - type: number
      exclusiveMinimum: 0
      unit: s
    - type: array
      items:
        type: number
        exclusiveMinimum: 0
        unit: s
PowerLineFrequency:
  name: PowerLineFrequency
  display_name: Power Line Frequency
  description: |
    Frequency (in Hz) of the power grid at the geographical location of the
    instrument (for example, `50` or `60`).
  anyOf:
    - type: number
      exclusiveMinimum: 0
      unit: Hz
    - type: string
      enum:
        - n/a
PromptRate:
  name: PromptRate
  display_name: Prompt Rate
  description: |
    Prompt rate for each frame (same units as `Units`, for example, `"Bq/mL"`).
  type: array
  items:
    type: number
PulseSequenceDetails:
  name: PulseSequenceDetails
  display_name: Pulse Sequence Details
  description: |
    Information beyond pulse sequence type that identifies the specific pulse
    sequence used (for example,
    `"Standard Siemens Sequence distributed with the VB17 software"`,
    `"Siemens WIP ### version #.##,"` or
    `"Sequence written by X using a version compiled on MM/DD/YYYY"`).
  type: string
PulseSequencePulses:
  name: PulseSequencePulses
  display_name: Pulse Sequence Pulses
  description: |
    The list of pulses used in the pulse sequence.
    If this parameter is specified, the array MUST correspond to the array of timings in
    `"PulseSequenceTiming"`.
    That is, the length of both arrays MUST be equal.
    The strings MAY be of the format `<pulse_name>_R<time-bandwidth_product>`.
    For example, a sLASER sequence may be described as such:
    `["P10_R6", "HS4_R25", "HS4_R25", "HS4_R25", "HS4_R25"]`.
  type: array
  items:
    type: string
PulseSequenceTiming:
  name: PulseSequenceTiming
  display_name: Pulse Sequence Timing
  description: |
    The time when each RF pulse of the pulse sequence was played out relative to
    the beginning of the pulse sequence, specified in seconds.
  type: array
  items:
    type: number
PulseSequenceType:
  name: PulseSequenceType
  display_name: Pulse Sequence Type
  description: |
    A general description of the pulse sequence used for the scan.
  type: string
Purity:
  name: Purity
  display_name: Purity
  description: |
    Purity of the radiolabeled compound (between 0 and 100%).
  type: number
  minimum: 0
  maximum: 100
RandomRate:
  name: RandomRate
  display_name: Random Rate
  description: |
    Random rate for each frame (same units as `"Units"`, for example, `"Bq/mL"`).
  type: array
  items:
    type: number
RawSources:
  name: RawSources
  display_name: Raw Sources
  description: |
    A list of paths relative to dataset root pointing to the BIDS-Raw file(s)
    that were used in the creation of this derivative.
    This field is DEPRECATED, and this metadata SHOULD be recorded in the
    `Sources` field using [BIDS URIs](SPEC_ROOT/common-principles.md#bids-uri)
    to distinguish sources from different datasets.
  type: array
  items:
    type: string
    format: dataset_relative
ReceiveCoilActiveElements:
  name: ReceiveCoilActiveElements
  display_name: Receive Coil Active Elements
  description: |
    Information describing the active/selected elements of the receiver coil.
    This does not correspond to a tag in the DICOM ontology.
    The vendor-defined terminology for active coil elements can go in this field.
  type: string
ReceiveCoilName:
  name: ReceiveCoilName
  display_name: Receive Coil Name
  description: |
    Information describing the receiver coil.
    Corresponds to DICOM Tag 0018, 1250 `Receive Coil Name`,
    although not all vendors populate that DICOM Tag,
    in which case this field can be derived from an appropriate
    private DICOM field.
  type: string
ReceiveGain:
  name: ReceiveGain
  display_name: Receive Gain
  description: |
    The gain of the receive coil.
  anyOf:
    - type: number
    - type: array
      items:
        type: number
ReconFilterSize:
  name: ReconFilterSize
  display_name: Recon Filter Size
  description: |
    Kernel size of post-recon filter (FWHM) in default units `"mm"`.
  anyOf:
    - type: number
      unit: mm
    - type: array
      items:
        type: number
        unit: mm
ReconFilterType:
  name: ReconFilterType
  display_name: Recon Filter Type
  description: |
    Type of post-recon smoothing (for example, `["Shepp"]`).
  anyOf:
    - type: string
    - type: array
      items:
        type: string
ReconMethodImplementationVersion:
  name: ReconMethodImplementationVersion
  display_name: Recon Method Implementation Version
  description: |
    Identification for the software used, such as name and version.
  type: string
ReconMethodName:
  name: ReconMethodName
  display_name: Recon Method Name
  description: |
    Reconstruction method or algorithm (for example, `"3d-op-osem"`).
  type: string
ReconMethodParameterLabels:
  name: ReconMethodParameterLabels
  display_name: Recon Method Parameter Labels
  description: |
    Names of reconstruction parameters (for example, `["subsets", "iterations"]`).
  type: array
  items:
    type: string
ReconMethodParameterUnits:
  name: ReconMethodParameterUnits
  display_name: Recon Method Parameter Units
  description: |
    Unit of reconstruction parameters (for example, `["none", "none"]`).
  type: array
  items:
    type: string
    format: unit
ReconMethodParameterValues:
  name: ReconMethodParameterValues
  display_name: Recon Method Parameter Values
  description: |
    Values of reconstruction parameters (for example, `[21, 3]`).
  type: array
  items:
    type: number
RecordingDuration:
  name: RecordingDuration
  display_name: Recording Duration
  description: |
    Length of the recording in seconds (for example, `3600`).
  type: number
  unit: s
RecordingType:
  name: RecordingType
  display_name: Recording Type
  description: |
    Defines whether the recording is `"continuous"`, `"discontinuous"`, or
    `"epoched"`, where `"epoched"` is limited to time windows about events of
    interest (for example, stimulus presentations or subject responses).
  type: string
  enum:
    - continuous
    - epoched
    - discontinuous
ReferencesAndLinks:
  name: ReferencesAndLinks
  display_name: References And Links
  description: |
    List of references to publications that contain information on the dataset.
    A reference may be textual or a
    [URI](SPEC_ROOT/common-principles.md#uniform-resource-indicator).
  items:
    type: string
  type: array
ReferenceSignal:
  name: ReferenceSignal
  display_name: Reference Signal
  description: |
    The path(s) to the MRS reference file(s), if present, to which the associated
    MRS data file corresponds.
    Contains one or more [BIDS URIs](SPEC_ROOT/common-principles.md#bids-uri).
  anyOf:
    - type: string
    - type: array
      items:
        type: string
RepetitionTime:
  name: RepetitionTime
  display_name: Repetition Time
  description: |
    The time in seconds between the beginning of an acquisition of one volume
    and the beginning of acquisition of the volume following it (TR).
    When used in the context of functional acquisitions this parameter best
    corresponds to
    [DICOM Tag 0020, 0110](http://dicomlookup.com/lookup.asp?sw=Tnumber&q=(0020,0110)):
    the "time delta between images in a
    dynamic of functional set of images" but may also be found in
    [DICOM Tag 0018, 0080](http://dicomlookup.com/lookup.asp?sw=Tnumber&q=(0018,0080)):
    "the period of time in msec between the beginning
    of a pulse sequence and the beginning of the succeeding
    (essentially identical) pulse sequence".
    This definition includes time between scans (when no data has been acquired)
    in case of sparse acquisition schemes.
    This value MUST be consistent with the 'pixdim[4]' field (after accounting
    for units stored in 'xyzt_units' field) in the NIfTI header.
    This field is mutually exclusive with VolumeTiming.
  type: number
  exclusiveMinimum: 0
  unit: s
RepetitionTime__mrs:
  name: RepetitionTime
  display_name: Repetition Time
  description: |
    The time between repetitions (TR), specified in seconds.
    For dynamic acquisitions, such as cardiac-triggered acquisitions where the TR
    may differ over the scan, an array of numbers can be used.
  anyOf:
    - type: number
      minimum: 0
      unit: s
    - type: array
      items:
        type: number
        minimum: 0
        unit: s
RepetitionTimeExcitation:
  name: RepetitionTimeExcitation
  display_name: Repetition Time Excitation
  description: |
    The interval, in seconds, between two successive excitations.
    [DICOM Tag 0018, 0080](http://dicomlookup.com/lookup.asp?sw=Tnumber&q=(0018,0080))
    best refers to this parameter.
    This field may be used together with the `"RepetitionTimePreparation"` for
    certain use cases, such as
    [MP2RAGE](https://doi.org/10.1016/j.neuroimage.2009.10.002).
    Use `RepetitionTimeExcitation` (in combination with
    `"RepetitionTimePreparation"` if needed) for anatomy imaging data rather than
    `"RepetitionTime"` as it is already defined as the amount of time that it takes
    to acquire a single volume in the
    [task imaging data](SPEC_ROOT/modality-specific-files/magnetic-resonance-\
    imaging-data.md#task-including-resting-state-imaging-data)
    section.
  type: number
  minimum: 0
  unit: s
RepetitionTimePreparation:
  name: RepetitionTimePreparation
  display_name: Repetition Time Preparation
  description: |
    The interval, in seconds, that it takes a preparation pulse block to
    re-appear at the beginning of the succeeding (essentially identical) pulse
    sequence block.
    The data type number may apply to files from any MRI modality concerned with
    a single value for this field.
    The data type array provides a value for each volume in a 4D dataset and
    should only be used when the volume timing is critical for interpretation of
    the data, such as in
    [ASL](SPEC_ROOT/modality-specific-files/magnetic-resonance-imaging-data.md\
    #arterial-spin-labeling-perfusion-data).
  anyOf:
    - type: number
      minimum: 0
      unit: s
    - type: array
      items:
        type: number
        minimum: 0
        unit: s
Resolution:
  name: Resolution
  display_name: Resolution
  description: |
    Specifies the interpretation of the resolution keyword.
    If an object is used, then the keys should be values for the `res` entity
    and values should be descriptions of those `res` values.
  anyOf:
    - type: string
    - type: object
      additionalProperties:
        type: string
ResonantNucleus:
  name: ResonantNucleus
  display_name: Resonant Nucleus
  description: |
    The isotope of interest of an MR experiment (for example, `"1H"`, `"13C"`, `"31P"`).
    For multi-nuclei experiments such as <sup>1</sup>H-[<sup>13</sup>C] MR,
    an array can be used: `["1H", "13C"]`.
    Corresponds to DICOM Tag 0018, 9100 `Resonant Nucleus`.
  anyOf:
    - type: string
    - type: array
      items:
        type: string
SEEGChannelCount:
  name: SEEGChannelCount
  display_name: SEEG Channel Count
  description: |
    Number of SEEG channels.
  type: integer
  minimum: 0
SampleEmbedding:
  name: SampleEmbedding
  display_name: Sample Embedding
  description: |
    Description of the tissue sample embedding (for example: `"Epoxy resin"`).
  type: string
SampleEnvironment:
  name: SampleEnvironment
  display_name: Sample Environment
  description: |
    Environment in which the sample was imaged. MUST be one of: `"in vivo"`, `"ex vivo"`
    or `"in vitro"`.
  type: string
  enum:
    - in vivo
    - ex vivo
    - in vitro
SampleExtractionInstitution:
  name: SampleExtractionInstitution
  display_name: Sample Extraction Institution
  description: |
    The name of the institution in charge of the extraction of the sample,
    if different from the institution in charge of the equipment that produced the image.
  type: string
SampleExtractionProtocol:
  name: SampleExtractionProtocol
  display_name: Sample Extraction Protocol
  description: |
    Description of the sample extraction protocol or
    [URI](SPEC_ROOT/common-principles.md#uniform-resource-indicator)
    (for example from [protocols.io](https://www.protocols.io/)).
  type: string
SampleFixation:
  name: SampleFixation
  display_name: Sample Fixation
  description: |
    Description of the tissue sample fixation
    (for example: `"4% paraformaldehyde, 2% glutaraldehyde"`).
  type: string
SampleOrigin:
  name: SampleOrigin
  display_name: Sample Origin
  description: |
    Describes from which tissue the genetic information was extracted.
  type: string
  enum:
    - blood
    - saliva
    - brain
    - csf
    - breast milk
    - bile
    - amniotic fluid
    - other biospecimen
SamplePrimaryAntibody:
  name: SamplePrimaryAntibody
  display_name: Sample Primary Antibody
  description: |
    Description(s) of the primary antibody used for immunostaining.
    Either an [RRID](https://scicrunch.org/resources) or the name, supplier and catalogue
    number of a commercial antibody.
    For non-commercial antibodies either an [RRID](https://scicrunch.org/resources) or the
    host-animal and immunogen used (for examples: `"RRID:AB_2122563"` or
    `"Rabbit anti-Human HTR5A Polyclonal Antibody, Invitrogen, Catalog # PA1-2453"`).
    MAY be an array of strings if different antibodies are used in each channel of the file.
  anyOf:
    - type: string
    - type: array
      items:
        type: string
SampleSecondaryAntibody:
  name: SampleSecondaryAntibody
  display_name: Sample Secondary Antibody
  description: |
    Description(s) of the secondary antibody used for immunostaining.
    Either an [RRID](https://scicrunch.org/resources) or the name, supplier and catalogue
    number of a commercial antibody.
    For non-commercial antibodies either an [RRID](https://scicrunch.org/resources) or the
    host-animal and immunogen used (for examples: `"RRID:AB_228322"` or
    `"Goat anti-Mouse IgM Secondary Antibody, Invitrogen, Catalog # 31172"`).
    MAY be an array of strings if different antibodies are used in each channel of the file.
  anyOf:
    - type: string
    - type: array
      items:
        type: string
SampleStaining:
  name: SampleStaining
  display_name: Sample Staining
  description: |
    Description(s) of the tissue sample staining (for example: `"Osmium"`).
    MAY be an array of strings if different stains are used in each channel of the file
    (for example: `["LFB", "PLP"]`).
  anyOf:
    - type: string
    - type: array
      items:
        type: string
SamplingFrequency:
  name: SamplingFrequency
  display_name: Sampling Frequency
  description: |
    Sampling frequency (in Hz) of all the data in the recording,
    regardless of their type (for example, `2400`).
  type: number
  unit: Hz
SamplingFrequency__nirs:
  name: SamplingFrequency
  display_name: Sampling Frequency
  description: |
    Sampling frequency (in Hz) of all the data in the recording,
    regardless of their type (for example, `2400`).
  anyOf:
    - type: number
      unit: Hz
    - type: string
      enum:
        - n/a
ScaleFactor:
  name: ScaleFactor
  display_name: Scale Factor
  description: |
    Scale factor for each frame. This field MUST be defined if the imaging data (`.nii[.gz]`) are scaled.
    If this field is not defined, then it is assumed that the scaling factor is 1. Defining this field
    when the scaling factor is 1 is RECOMMENDED, for the sake of clarity.
  type: array
  items:
    type: number
ScanDate:
  name: ScanDate
  display_name: Scan Date
  description: |
    Date of scan in the format `"YYYY-MM-DD[Z]"`.
    This field is DEPRECATED, and this metadata SHOULD be recorded in the `acq_time` column of the
    corresponding [Scans file](SPEC_ROOT/modality-agnostic-files.md#scans-file).
  type: string
  format: date
ScanOptions:
  name: ScanOptions
  display_name: Scan Options
  description: |
    Parameters of ScanningSequence.
    Corresponds to DICOM Tag 0018, 0022 `Scan Options`.
  anyOf:
    - type: string
    - type: array
      items:
        type: string
ScanStart:
  name: ScanStart
  display_name: Scan Start
  description: |
    Time of start of scan with respect to `TimeZero` in the default unit seconds.
  type: number
  unit: s
ScanningSequence:
  name: ScanningSequence
  display_name: Scanning Sequence
  description: |
    Description of the type of data acquired.
    Corresponds to DICOM Tag 0018, 0020 `Scanning Sequence`.
  anyOf:
    - type: string
    - type: array
      items:
        type: string
ScanningSequence__mrs:
  name: ScanningSequence
  display_name: Scanning Sequence
  description: |
    Description of the type of data acquired.
  type: string
  enum:
    - SVS
    - MRSI
    - Unlocalized MRS
ScatterFraction:
  name: ScatterFraction
  display_name: Scatter Fraction
  description: |
    Scatter fraction for each frame (Units: 0-100%).
  type: array
  items:
    type: number
    minimum: 0
    maximum: 100
ScreenDistance:
  name: ScreenDistance
  display_name: Screen Distance
  description: |
    Distance between the participant's eye and the screen. If no screen was used, use `n/a`.
  anyOf:
    - type: number
      unit: m
    - type: string
      enum:
        - n/a
ScreenRefreshRate:
  name: ScreenRefreshRate
  display_name: Screen Refresh Rate
  description: |
    Refresh rate of the screen (when used), in Hertz (equivalent to frames per second, "FPS").
  type: number
  unit: Hz
ScreenResolution:
  name: ScreenResolution
  display_name: Screen Resolution
  description: |
    Screen resolution in pixel
    (for example `[1920, 1200]` for a screen of 1920-width by 1080-height pixels),
    if no screen use `n/a`.
  anyOf:
    - type: array
      items:
        type: integer
        minItems: 2
        maxItems: 2
    - type: string
      enum:
        - n/a
ScreenSize:
  name: ScreenSize
  display_name: Screen Size
  description: |
    Screen size in m, excluding potential screen borders
    (for example `[0.472, 0.295]` for a screen of 47.2-width by 29.5-height cm),
    if no screen use `n/a`.
  anyOf:
    - type: array
      items:
        type: number
        unit: m
        minItems: 2
        maxItems: 2
    - type: string
      enum:
        - n/a
SequenceName:
  name: SequenceName
  display_name: Sequence Name
  description: |
    Manufacturer's designation of the sequence name.
    Corresponds to DICOM Tag 0018, 0024 `Sequence Name`.
  type: string
SequenceVariant:
  name: SequenceVariant
  display_name: Sequence Variant
  description: |
    Variant of the ScanningSequence.
    Corresponds to DICOM Tag 0018, 0021 `Sequence Variant`.
  anyOf:
    - type: string
    - type: array
      items:
        type: string
ShortChannelCount:
  name: ShortChannelCount
  display_name: Short Channel Count
  description: |
    The number of short channels. 0 indicates no short channels.
  type: integer
  minimum: 0
SinglesRate:
  name: SinglesRate
  display_name: Singles Rate
  description: |
    Singles rate for each frame (same units as `Units`, for example, `"Bq/mL"`).
  type: array
  items:
    type: number
SkullStripped:
  name: SkullStripped
  display_name: Skull Stripped
  description: |
    Whether the volume was skull stripped (non-brain voxels set to zero) or not.
  type: boolean
SliceEncodingDirection:
  name: SliceEncodingDirection
  display_name: Slice Encoding Direction
  description: |
    The axis of the NIfTI data along which slices were acquired,
    and the direction in which `"SliceTiming"` is defined with respect to.
    `i`, `j`, `k` identifiers correspond to the first, second and third axis of
    the data in the NIfTI file.
    A `-` sign indicates that the contents of `"SliceTiming"` are defined in
    reverse order - that is, the first entry corresponds to the slice with the
    largest index, and the final entry corresponds to slice index zero.
    When present, the axis defined by `"SliceEncodingDirection"` needs to be
    consistent with the `slice_dim` field in the NIfTI header.
    When absent, the entries in `"SliceTiming"` must be in the order of increasing
    slice index as defined by the NIfTI header.
  type: string
  enum:
    - i
    - j
    - k
    - i-
    - j-
    - k-
SliceThickness:
  name: SliceThickness
  display_name: Slice Thickness
  description: |
    Slice thickness of the tissue sample in the unit micrometers (`"um"`) (for example: `5`).
  type: number
  unit: um
  exclusiveMinimum: 0
SliceTiming:
  name: SliceTiming
  display_name: Slice Timing
  description: |
    The time at which each slice was acquired within each volume (frame) of the
    acquisition.
    Slice timing is not slice order -- rather, it is a list of times containing
    the time (in seconds) of each slice acquisition in relation to the beginning
    of volume acquisition.
    The list goes through the slices along the slice axis in the slice encoding
    dimension (see below).
    Note that to ensure the proper interpretation of the `"SliceTiming"` field,
    it is important to check if the OPTIONAL `SliceEncodingDirection` exists.
    In particular, if `"SliceEncodingDirection"` is negative,
    the entries in `"SliceTiming"` are defined in reverse order with respect to the
    slice axis, such that the final entry in the `"SliceTiming"` list is the time
    of acquisition of slice 0. Without this parameter slice time correction will
    not be possible.
  type: array
  items:
    type: number
    minimum: 0
    unit: s
SoftwareFilters:
  name: SoftwareFilters
  display_name: Software Filters
  description: |
    [Object](https://www.json.org/json-en.html)
    of temporal software filters applied, or `"n/a"` if the data is
    not available.
    Each key-value pair in the JSON object is a name of the filter and an object
    in which its parameters are defined as key-value pairs
    (for example, `{"Anti-aliasing filter":
    {"half-amplitude cutoff (Hz)": 500, "Roll-off": "6dB/Octave"}}`).
  anyOf:
    - type: object
      additionalProperties:
        type: object
    - type: string
      enum:
        - n/a
SoftwareName:
  name: SoftwareName
  display_name: Software Name
  description: |
    Name of the software that was used to present the stimuli.
  type: string
SoftwareRRID:
  name: SoftwareRRID
  display_name: SoftwareRRID
  description: |
    [Research Resource Identifier](https://scicrunch.org/resources) of the
    software that was used to present the stimuli.
    Examples: The RRID for Psychtoolbox is 'SCR_002881',
    and that of PsychoPy is 'SCR_006571'.
  type: string
  format: rrid
SoftwareVersion:
  name: SoftwareVersion
  display_name: Software Version
  description: |
    Version of the software that was used to present the stimuli.
  type: string
SoftwareVersions:
  name: SoftwareVersions
  display_name: Software Versions
  description: |
    Manufacturer's designation of software version of the equipment that produced
    the measurements.
  type: string
SourceDatasets:
  name: SourceDatasets
  display_name: Source Datasets
  description: |
    Used to specify the locations and relevant attributes of all source datasets.
    Valid keys in each object include `"URL"`, `"DOI"` (see
    [URI](SPEC_ROOT/common-principles.md#uniform-resource-indicator)), and
    `"Version"` with
    [string](https://www.w3schools.com/js/js_json_datatypes.asp)
    values.
  type: array
  items:
    type: object
    properties:
      URL:
        type: string
        format: uri
      DOI:
        type: string
      Version:
        type: string
Sources:
  name: Sources
  display_name: Sources
  description: |
    A list of files with the paths specified using
    [BIDS URIs](SPEC_ROOT/common-principles.md#bids-uri);
    these files were directly used in the creation of this derivative data file.
    For example, if a derivative A is used in the creation of another
    derivative B, which is in turn used to generate C in a chain of A->B->C,
    C should only list B in `"Sources"`, and B should only list A in `"Sources"`.
    However, in case both X and Y are directly used in the creation of Z,
    then Z should list X and Y in `"Sources"`,
    regardless of whether X was used to generate Y.
    Using paths specified relative to the dataset root is
    [DEPRECATED](SPEC_ROOT/common-principles.md#definitions).
  type: array
  items:
    type: string
    format: dataset_relative
SourceType:
  name: SourceType
  display_name: Source Type
  description: |
    Type of source. Preferably a specific model/part number is supplied.
    This is a freeform description, but the following keywords are suggested:
    `"LED"`, `"LASER"`, `"VCSEL"`. If individual channels have different SourceType,
    then the field here should be specified as "mixed"
    and this column should be included in optodes.tsv.
  type: string
SpatialReference:
  name: SpatialReference
  display_name: Spatial Reference
  description: |
    For images with a single reference, the value MUST be a single string.
    For images with multiple references, such as surface and volume references,
    a JSON object MUST be used.
  anyOf:
    - type: string
      enum:
        - orig
    - type: string
      format: uri
    - type: string
      format: dataset_relative
    - type: object
      additionalProperties:
        anyOf:
          - type: string
            enum:
              - orig
          - type: string
            format: uri
          - type: string
            format: dataset_relative
SpecificRadioactivity:
  name: SpecificRadioactivity
  display_name: Specific Radioactivity
  description: |
    Specific activity of compound injected.
    **Note this is not required for an FDG acquisition, since it is not available,
    and SHOULD be set to `"n/a"`**.
  anyOf:
    - type: number
    - type: string
      enum:
        - n/a
SpecificRadioactivityMeasTime:
  name: SpecificRadioactivityMeasTime
  display_name: Specific Radioactivity Measurement Time
  description: |
    Time to which specific radioactivity measurement above applies in the default
    unit `"hh:mm:ss"`.
  type: string
  format: time
SpecificRadioactivityUnits:
  name: SpecificRadioactivityUnits
  display_name: Specific Radioactivity Units
  description: |
    Unit format of specified specific radioactivity (for example, `"Bq/g"`).
    **Note this is not required for an FDG acquisition, since it is not available,
    and SHOULD be set to `"n/a"`**.
  anyOf:
    - type: string
      format: unit
    - type: string
      enum:
        - n/a
SpectralWidth:
  name: SpectralWidth
  display_name: Spectral Width
  description: |
    The spectral bandwidth of the MR signal that is sampled, specified in Hz.
    Corresponds to DICOM Tag 0018, 9052 `Spectral Width`.
  type: number
SpectrometerFrequency:
  name: SpectrometerFrequency
  display_name: Spectrometer Frequency
  description: |
    The frequency of the spectrometer, specified in MHz.
    For example, this could be `127.764` for a 3T scanner tuned
    to the resonant frequency of <sup>1</sup>H.
    For multi-nuclei experiments such as <sup>1</sup>H-[<sup>13</sup>C] MR at 3T,
    an array can be used: `[127.731, 32.125]`.
  anyOf:
    - type: number
    - type: array
      items:
        type: number
SpoilingGradientDuration:
  name: SpoilingGradientDuration
  display_name: Spoiling Gradient Duration
  description: |
    The duration of the spoiler gradient lobe in seconds.
    The duration of a trapezoidal lobe is defined as the summation of ramp-up
    and plateau times.
  type: number
  unit: s
SpoilingGradientMoment:
  name: SpoilingGradientMoment
  display_name: Spoiling Gradient Moment
  description: |
    Zeroth moment of the spoiler gradient lobe in
    millitesla times second per meter (mT.s/m).
  type: number
  unit: mT.s/m
SpoilingRFPhaseIncrement:
  name: SpoilingRFPhaseIncrement
  display_name: Spoiling RF Phase Increment
  description: |
    The amount of incrementation described in degrees,
    which is applied to the phase of the excitation pulse at each TR period for
    achieving RF spoiling.
  type: number
  unit: degrees
SpoilingState:
  name: SpoilingState
  display_name: Spoiling State
  description: |
    Boolean stating whether the pulse sequence uses any type of spoiling
    strategy to suppress residual transverse magnetization.
  type: boolean
SpoilingType:
  name: SpoilingType
  display_name: Spoiling Type
  description: |
    Specifies which spoiling method(s) are used by a spoiled sequence.
  type: string
  enum:
    - RF
    - GRADIENT
    - COMBINED
StartTime:
  name: StartTime
  display_name: Start Time
  description: |
    Start time in seconds in relation to the start of acquisition of the first
    data sample in the corresponding neural dataset (negative values are allowed).
  type: number
  unit: s
StationName:
  name: StationName
  display_name: Station Name
  description: |
    Institution defined name of the machine that produced the measurements.
  type: string
StimulusPresentation:
  name: StimulusPresentation
  display_name: Stimulus Presentation
  description: |
    Object containing key-value pairs related to the software used to present
    the stimuli during the experiment.
  type: object
  recommended_fields:
    - OperatingSystem
    - ScreenDistance
    - ScreenRefreshRate
    - ScreenResolution
    - ScreenSize
    - SoftwareName
    - SoftwareRRID
    - SoftwareVersion
    - Code
  properties:
    OperatingSystem:
      $ref: objects.metadata.OperatingSystem
    ScreenDistance:
      $ref: objects.metadata.ScreenDistance
    ScreenRefreshRate:
      $ref: objects.metadata.ScreenRefreshRate
    ScreenResolution:
      $ref: objects.metadata.ScreenResolution
    ScreenSize:
      $ref: objects.metadata.ScreenSize
    SoftwareName:
      $ref: objects.metadata.SoftwareName
    SoftwareRRID:
      $ref: objects.metadata.SoftwareRRID
    SoftwareVersion:
      $ref: objects.metadata.SoftwareVersion
    Code:
      $ref: objects.metadata.Code
SubjectArtefactDescription:
  name: SubjectArtefactDescription
  display_name: Subject Artefact Description
  description: |
    Freeform description of the observed subject artefact and its possible cause
    (for example, `"Vagus Nerve Stimulator"`, `"non-removable implant"`).
    If this field is set to `"n/a"`, it will be interpreted as absence of major
    source of artifacts except cardiac and blinks.
  type: string
TaskDescription:
  name: TaskDescription
  display_name: Task Description
  description: |
    Longer description of the task.
  type: string
TaskName:
  name: TaskName
  display_name: Task Name
  description: |
    Name of the task.
    No two tasks should have the same name.
    The task label included in the file name is derived from this `"TaskName"` field
    by removing all non-alphanumeric characters (that is, all except those matching `[0-9a-zA-Z]`).
    For example `"TaskName"` `"faces n-back"` or `"head nodding" will correspond to task labels
    `facesnback` and `headnodding`, respectively.
  type: string
TermURL:
  name: TermURL
  display_name: TermURL
  description: |
    URL pointing to a formal definition of this type of data in an ontology
    available on the web.
  type: string
TimeZero:
  name: TimeZero
  display_name: Time Zero
  description: |
    Time zero to which all scan and/or blood measurements have been adjusted to,
    in the unit "hh:mm:ss".
    This should be equal to `"InjectionStart"` or `"ScanStart"`.
  type: string
  format: time
TissueDeformationScaling:
  name: TissueDeformationScaling
  display_name: Tissue Deformation Scaling
  description: |
    Estimated deformation of the tissue, given as a percentage of the original
    tissue size (for examples: for a shrinkage of 3%, the value is `97`;
    and for an expansion of 100%, the value is `200`).
  type: number
  exclusiveMinimum: 0
TissueOrigin:
  name: TissueOrigin
  display_name: Tissue Origin
  description: |
    Describes the type of tissue analyzed for `"SampleOrigin"` `brain`.
  type: string
  enum:
    - gray matter
    - white matter
    - csf
    - meninges
    - macrovascular
    - microvascular
TotalAcquiredPairs:
  name: TotalAcquiredPairs
  display_name: Total Acquired Pairs
  description: |
    The total number of acquired `control`-`label` pairs.
    A single pair consists of a single `control` and a single `label` image.
  type: number
  exclusiveMinimum: 0
TotalReadoutTime:
  name: TotalReadoutTime
  display_name: Total Readout Time
  description: |
    This is actually the "effective" total readout time,
    defined as the readout duration, specified in seconds,
    that would have generated data with the given level of distortion.
    It is NOT the actual, physical duration of the readout train.
    If `"EffectiveEchoSpacing"` has been properly computed,
    it is just `EffectiveEchoSpacing * (ReconMatrixPE - 1)`.
  type: number
  unit: s
TracerMolecularWeight:
  name: TracerMolecularWeight
  display_name: Tracer Molecular Weight
  description: |
    Accurate molecular weight of the tracer used.
  type: number
TracerMolecularWeightUnits:
  name: TracerMolecularWeightUnits
  display_name: Tracer Molecular Weight Units
  description: |
    Unit of the molecular weights measurement (for example, `"g/mol"`).
  type: string
  format: unit
TracerName:
  name: TracerName
  display_name: Tracer Name
  description: |
    Name of the tracer compound used (for example, `"CIMBI-36"`)
  type: string
TracerRadLex:
  name: TracerRadLex
  display_name: Tracer Rad Lex
  description: |
    ID of the tracer compound from the RadLex Ontology.
  type: string
TracerRadionuclide:
  name: TracerRadionuclide
  display_name: Tracer Radionuclide
  description: |
    Radioisotope labelling tracer (for example, `"C11"`).
  type: string
TracerSNOMED:
  name: TracerSNOMED
  display_name: TracerSNOMED
  description: |
    ID of the tracer compound from the SNOMED Ontology
    (subclass of Radioactive isotope).
  type: string
TriggerChannelCount:
  name: TriggerChannelCount
  display_name: Trigger Channel Count
  description: |
    Number of channels for digital (binary TTL) triggers or analog equivalents (TTL in volt).
    Corresponds to the `TRIG` channel type.
  type: integer
  minimum: 0
TubingLength:
  name: TubingLength
  display_name: Tubing Length
  description: |
    The length of the blood tubing, from the subject to the detector in meters.
  type: number
  unit: m
TubingType:
  name: TubingType
  display_name: Tubing Type
  description: |
    Description of the type of tubing used, ideally including the material and
    (internal) diameter.
  type: string
Type:
  name: Type
  display_name: Type
  description: |
    Short identifier of the mask.
    The value `"Brain"` refers to a brain mask.
    The value `"Lesion"` refers to a lesion mask.
    The value `"Face"` refers to a face mask.
    The value `"ROI"` refers to a region of interest mask.
  type: string
  enum:
    - Brain
    - Lesion
    - Face
    - ROI
Units:
  name: Units
  display_name: Units
  description: |
    Measurement units for the associated file.
    SI units in CMIXF formatting are RECOMMENDED
    (see [Units](SPEC_ROOT/common-principles.md#units)).
  type: string
  format: unit
VascularCrushing:
  name: VascularCrushing
  display_name: Vascular Crushing
  description: |
    Boolean indicating if Vascular Crushing is used.
    Corresponds to DICOM Tag 0018, 9259 `ASL Crusher Flag`.
  type: boolean
VascularCrushingVENC:
  name: VascularCrushingVENC
  display_name: Vascular Crushing VENC
  description: |
    The crusher gradient strength, in centimeters per second.
    Specify either one number for the total time-series, or provide an array of
    numbers, for example when using QUASAR, using the value zero to identify
    volumes for which `VascularCrushing` was turned off.
    Corresponds to DICOM Tag 0018, 925A `ASL Crusher Flow Limit`.
  anyOf:
    - type: number
      unit: cm/s
    - type: array
      items:
        type: number
        unit: cm/s
VolumeAffineMatrix:
  name: VolumeAffineMatrix
  display_name: Volume Affine Matrix
  description: |
    A 4-by-4 matrix using identical conventions and coordinate system to
    the *{qs}form* NIfTI affine matrix to define the orientation,
    position, and size of an additional VOI.
    This VOI defines a spatial region in addition to the primary method of localization
    (encoded in the NIfTI header *{qs}form*).
    Typically not defined for data stored with a single spatial voxel or FID-MRSI.
    For example: `[[30, 0, 0, -30], [0, 30, -2.27, -72.67], [0, 2.27, 29.91, 5.47],
    [0, 0, 0, 1]]`.
  type: array
  minItems: 16
  maxItems: 16
  items:
    type: number
VolumeTiming:
  name: VolumeTiming
  display_name: Volume Timing
  description: |
    The time at which each volume was acquired during the acquisition.
    It is described using a list of times referring to the onset of each volume
    in the BOLD series.
    The list must have the same length as the BOLD series,
    and the values must be non-negative and monotonically increasing.
    This field is mutually exclusive with `"RepetitionTime"` and `"DelayTime"`.
    If defined, this requires acquisition time (TA) be defined via either
    `"SliceTiming"` or `"AcquisitionDuration"` be defined.
  type: array
  minItems: 1
  items:
    type: number
    unit: s
WaterSuppression:
  name: WaterSuppression
  display_name: Water Suppression
  description: |
    Boolean indicating whether water suppression was used prior to acquisition.
  type: boolean
WaterSuppressionTechnique:
  name: WaterSuppressionTechnique
  display_name: Water Suppression Technique
  description: |
    The name of the pulse sequence used for water suppression (for example, `"CHESS"`, `"VAPOR"`).
    If no water suppression was used (for example, when collecting a water-unsuppressed reference),
    set as `null`.
  type: string
WholeBloodAvail:
  name: WholeBloodAvail
  display_name: Whole Blood Avail
  description: |
    Boolean that specifies if whole blood measurements are available.
    If `true`, the `whole_blood_radioactivity` column MUST be present in the
    corresponding `*_blood.tsv` file.
  type: boolean
WithdrawalRate:
  name: WithdrawalRate
  display_name: Withdrawal Rate
  description: |
    The rate at which the blood was withdrawn from the subject.
    The unit of the specified withdrawal rate should be in `"mL/s"`.
  type: number
  unit: mL/s
_CoordUnits:
  type: string
  enum:
    - m
    - mm
    - cm
    - n/a
_EEGCoordSys:
  type: string
  enum:
    - CapTrak
    - EEGLAB
    - EEGLAB-HJ
    - Other
_GeneticLevelEnum:
  type: string
  enum:
    - Genetic
    - Genomic
    - Epigenomic
    - Transcriptomic
    - Metabolomic
    - Proteomic
_LandmarkCoordinates:
  type: object
  additionalProperties:
    type: array
    items:
      type: number
    minItems: 3
    maxItems: 3
_MEGCoordSys:
  type: string
  enum:
    - CTF
    - ElektaNeuromag
    - 4DBti
    - KitYokogawa
    - ChietiItab
    - Other
_StandardTemplateCoordSys:
  type: string
  enum:
    - ICBM452AirSpace
    - ICBM452Warp5Space
    - IXI549Space
    - fsaverage
    - fsaverageSym
    - fsLR
    - MNIColin27
    - MNI152Lin
    - MNI152NLin2009aSym
    - MNI152NLin2009bSym
    - MNI152NLin2009cSym
    - MNI152NLin2009aAsym
    - MNI152NLin2009bAsym
    - MNI152NLin2009cAsym
    - MNI152NLin6Sym
    - MNI152NLin6ASym
    - MNI305
    - NIHPD
    - OASIS30AntsOASISAnts
    - OASIS30Atropos
    - Talairach
    - UNCInfant
_StandardTemplateDeprecatedCoordSys:
  type: string
  enum:
    - fsaverage3
    - fsaverage4
    - fsaverage5
    - fsaverage6
    - fsaveragesym
    - UNCInfant0V21
    - UNCInfant1V21
    - UNCInfant2V21
    - UNCInfant0V22
    - UNCInfant1V22
    - UNCInfant2V22
    - UNCInfant0V23
    - UNCInfant1V23
    - UNCInfant2V23
_iEEGCoordSys:
  type: string
  enum:
    - Pixels
    - ACPC
    - Other
iEEGCoordinateProcessingDescription:
  name: iEEGCoordinateProcessingDescription
  display_name: iEEG Coordinate Processing Description
  description: |
    Has any post-processing (such as projection) been done on the electrode
    positions (for example, `"surface_projection"`, `"none"`).
  type: string
iEEGCoordinateProcessingReference:
  name: iEEGCoordinateProcessingReference
  display_name: iEEG Coordinate Processing Reference
  description: |
    A reference to a paper that defines in more detail the method used to
    localize the electrodes and to post-process the electrode positions.
  type: string
iEEGCoordinateSystem:
  name: iEEGCoordinateSystem
  display_name: iEEG Coordinate System
  description: |
    Defines the coordinate system for the iEEG sensors.
    See the
    [Coordinate Systems Appendix](SPEC_ROOT/appendices/coordinate-systems.md)
    for a list of restricted keywords for coordinate systems.
    If `"Other"`, provide definition of the coordinate system in
    `iEEGCoordinateSystemDescription`.
    If positions correspond to pixel indices in a 2D image
    (of either a volume-rendering, surface-rendering, operative photo, or
    operative drawing), this MUST be `"Pixels"`.
    For more information, see the section on
    [2D coordinate systems](SPEC_ROOT/modality-specific-files/intracranial\
    -electroencephalography.md#allowed-2d-coordinate-systems).
  anyOf:
    - $ref: objects.metadata._iEEGCoordSys
    - $ref: objects.metadata._StandardTemplateCoordSys
    - $ref: objects.metadata._StandardTemplateDeprecatedCoordSys
iEEGCoordinateSystemDescription:
  name: iEEGCoordinateSystemDescription
  display_name: iEEG Coordinate System Description
  description: |
    Free-form text description of the coordinate system.
    May also include a link to a documentation page or paper describing the
    system in greater detail.
  type: string
iEEGCoordinateUnits:
  name: iEEGCoordinateUnits
  display_name: iEEG Coordinate Units
  description: |
    Units of the `*_electrodes.tsv`.
    MUST be `"pixels"` if `iEEGCoordinateSystem` is `Pixels`.
  type: string
  enum:
    - m
    - mm
    - cm
    - pixels
    - n/a
iEEGElectrodeGroups:
  name: iEEGElectrodeGroups
  display_name: iEEG Electrode Groups
  description: |
    Field to describe the way electrodes are grouped into strips, grids or depth
    probes.
    For example, `"grid1: 10x8 grid on left temporal pole, strip2: 1x8 electrode
    strip on xxx"`.
  type: string
iEEGGround:
  name: iEEGGround
  display_name: iEEG Ground
  description: |
    Description of the location of the ground electrode
    (`"placed on right mastoid (M2)"`).
  type: string
iEEGPlacementScheme:
  name: iEEGPlacementScheme
  display_name: iEEG Placement Scheme
  description: |
    Freeform description of the placement of the iEEG electrodes.
    Left/right/bilateral/depth/surface
    (for example, `"left frontal grid and bilateral hippocampal depth"` or
    `"surface strip and STN depth"` or
    `"clinical indication bitemporal, bilateral temporal strips and left grid"`).
  type: string
iEEGReference:
  name: iEEGReference
  display_name: iEEG Reference
  description: |
    General description of the reference scheme used and (when applicable) of
    location of the reference electrode in the raw recordings
    (for example, `"left mastoid"`, `"bipolar"`,
    `"T01"` for electrode with name T01,
    `"intracranial electrode on top of a grid, not included with data"`,
    `"upside down electrode"`).
    If different channels have a different reference,
    this field should have a general description and the channel specific
    reference should be defined in the `channels.tsv` file.
  type: string