Proposal: measurementLists Group as alternative to many measurementList1...measurementList2 indexed groups

.github/workflows/wordlist.txt

@@ -281,3 +281,4 @@ dataOffset
 forihuelaespina
 StO
 StO2
+measurementLists

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 SNIRF uses the [Semantic Versioning](https://semver.org) scheme.
 
+### `2.0` In development
+* Add `nirs(i)/data(j)/measurementLists` as an alternative to the indexed-Group measurementList `nirs(i)/data(j)/measurementList(k)`.
 
 ### `v1.1`
 
@@ -22,7 +24,7 @@ SNIRF uses the [Semantic Versioning](https://semver.org) scheme.
 * Added language preventing `metaDataTags` sub-groups
 * Added notice that the summary table is intended to be machine-readable
 * Removed local channel indexing owing to incomplete specification.
-  
+
 ### `v1.0` (September 23 2021)
 
 [View this version of the specification](https://github.com/fNIRS/snirf/blob/v1.0/snirf_specification.md)  

snirf_specification.md

@@ -30,6 +30,18 @@ Shared Near Infrared Spectroscopy Format (SNIRF) Specification
        * [data.measurementList.dataTypeIndex](#nirsidatajmeasurementlistkdatatypeindex)
        * [data.measurementList.sourcePower](#nirsidatajmeasurementlistksourcepower)
        * [data.measurementList.detectorGain](#nirsidatajmeasurementlistkdetectorgain)
+	   * [data.measurementLists](#nirsidatajmeasurementlists)
+	   * [data.measurementLists.sourceIndex](#nirsidatajmeasurementlistssourceindex)
+       * [data.measurementLists.detectorIndex](#nirsidatajmeasurementlistsdetectorindex)
+       * [data.measurementLists.wavelengthIndex](#nirsidatajmeasurementlistswavelengthindex)
+       * [data.measurementLists.wavelengthActual](#nirsidatajmeasurementlistswavelengthactual)
+       * [data.measurementLists.wavelengthEmissionActual](#nirsidatajmeasurementlistswavelengthemissionactual)
+       * [data.measurementLists.dataType](#nirsidatajmeasurementlistsdatatype)
+       * [data.measurementLists.dataUnit](#nirsidatajmeasurementlistsdataunit)
+       * [data.measurementLists.dataTypeLabel](#nirsidatajmeasurementlistsdatatypelabel)
+       * [data.measurementLists.dataTypeIndex](#nirsidatajmeasurementlistsdatatypeindex)
+       * [data.measurementLists.sourcePower](#nirsidatajmeasurementlistssourcepower)
+       * [data.measurementLists.detectorGain](#nirsidatajmeasurementlistsdetectorgain)
        * [stim](#nirsistimj)
        * [stim.name](#nirsistimjname)
        * [stim.data](#nirsistimjdata)
@@ -170,6 +182,18 @@ Note that this table serves as machine-readable schema for the SNIRF format. Its
 |            `dataTypeIndex`            | * Data type index for a given channel        |   `<i>`      * |
 |            `sourcePower`              | * Source power for a given channel           |   `<f>`        |
 |            `detectorGain`             | * Detector gain for a given channel          |   `<f>`        |
+|        `measurementLists`             | * source-detector information                |  `{.}`       * |
+|            `sourceIndex`              | * Source index for each channel              |   `[<i>,...]`* |
+|            `detectorIndex`            | * Detector index for each channel            |   `[<i>,...]`* |
+|            `wavelengthIndex`          | * Wavelength index for each channel          |   `[<i>,...]`* |
+|            `wavelengthActual`         | * Actual wavelength for each channel         |   `[<f>,...]`  |
+|            `wavelengthEmissionActual` | * Actual emission wavelength for each channel|   `[<f>,...]`  |
+|            `dataType`                 | * Data type for each channel                 |   `[<i>,...]`* |
+|            `dataUnit`                 | * SI unit for each channel                   |   `["s",...]`  |
+|            `dataTypeLabel`            | * Data type name for each channel            |   `["s",...]`  |
+|            `dataTypeIndex`            | * Data type index for each channel           |   `[<i>,...]`* |
+|            `sourcePower`              | * Source power for each channel              |   `[<f>,...]`  |
+|            `detectorGain`             | * Detector gain for each channel             |   `[<f>,...]`  |
 |     `stim{i}`                         | * Root-group for stimulus measurements       |   `{i}`        |
 |         `name`                        | * Name of the stimulus data                  |   `"s"`      + |
 |         `data`                        | * Data stream of the stimulus channel        | `[[<f>,...]]` +|
@@ -411,7 +435,7 @@ a time spacing of 0.2 (s) indicates a sampling rate of 5 Hz.
 Chunked data is allowed to support real-time streaming of data in this array.
 
 #### /nirs(i)/data(j)/measurementList(k) 
-* **Presence**: required
+* **Presence**: required if `measurementLists` is not present
 * **Type**:  indexed group
 * **Location**: `/nirs(i)/data(j)/measurementList(k)`
 
@@ -537,6 +561,94 @@ As described below, optional variables `probe.sourceLabels` and
 `probe.detectorLabels` are provided for indicating the instrument specific 
 label for sources and detectors.
 
+#### /nirs(i)/data(j)/measurementLists
+* **Presence**: required if measurementList is not present
+* **Type**:  group
+* **Location**: `/nirs(i)/data(j)/measurementLists`
+
+The group for measurement list variables which map the data array onto the probe geometry (sources and detectors), data type, and wavelength. This group's datasets are arrays with size `<number of channels>`, with each position describing the corresponding column in the data matrix. (i.e. the values at `measurementLists/sourceIndex(3)` and `measurementLists/detectorIndex(3)` correspond to `dataTimeSeries(:,3)`).
+
+This group is required only if the indexed-group format `/nirs(i)/data(j)/measurementList(k)` is not used to encode the measurement list. `measurementLists` is an alternative that may offer better performance for larger probes.
+
+The arrays of `measurementLists` are:
+
+#### /nirs(i)/data(j)/measurementLists/sourceIndex 
+* **Presence**: required if measurementLists is present
+* **Type**:  integer 1-D array
+* **Location**: `/nirs(i)/data(j)/measurementLists/sourceIndex`
+
+Source indices for each channel. A 1-D array with length equal to the size of the second dimension of `/nirs(i)/data(j)/dataTimeSeries`.
+
+#### /nirs(i)/data(j)/measurementLists/detectorIndex 
+* **Presence**: required if measurementLists is present
+* **Type**:  integer 1-D array
+* **Location**: `/nirs(i)/data(j)/measurementLists/detectorIndex`
+
+Detector indices for each channel. A 1-D array with length equal to the size of the second dimension of `/nirs(i)/data(j)/dataTimeSeries`.
+
+#### /nirs(i)/data(j)/measurementLists/wavelengthIndex 
+* **Presence**: required if measurementLists is present
+* **Type**:  integer 1-D array
+* **Location**: `/nirs(i)/data(j)/measurementLists/wavelengthIndex`
+
+Index of the "nominal" wavelength (in `probe.wavelengths`) for each channel. A 1-D array with length equal to the size of the second dimension of `/nirs(i)/data(j)/dataTimeSeries`.
+
+#### /nirs(i)/data(j)/measurementLists/wavelengthActual 
+* **Presence**: optional
+* **Type**:  numeric 1-D array
+* **Location**: `/nirs(i)/data(j)/measurementLists/wavelengthActual`
+
+Actual (measured) wavelength in nm, if available, for the source in each channel. A 1-D array with length equal to the size of the second dimension of `/nirs(i)/data(j)/dataTimeSeries`.
+
+#### /nirs(i)/data(j)/measurementLists/wavelengthEmissionActual
+* **Presence**: optional
+* **Type**:  numeric 1-D array
+* **Location**: `/nirs(i)/data(j)/measurementLists/wavelengthEmissionActual`
+
+Actual (measured) emission wavelength in nm, if available, for the source in each channel. A 1-D array with length equal to the size of the second dimension of `/nirs(i)/data(j)/dataTimeSeries`.
+
+#### /nirs(i)/data(j)/measurementLists/dataType 
+* **Presence**: required if measurementLists is present
+* **Type**:  integer 1-D array
+* **Location**: `/nirs(i)/data(j)/measurementLists/dataType`
+
+A 1-D array with length equal to the size of the second dimension of `/nirs(i)/data(j)/dataTimeSeries`. See Appendix for list of possible values.
+
+#### /nirs(i)/data(j)/measurementLists/dataUnit 
+* **Presence**: optional
+* **Type**:  string 1-D array
+* **Location**: `/nirs(i)/data(j)/measurementLists/dataUnit`
+
+International System of Units (SI units) identifier for each channel. A 1-D array with length equal to the size of the second dimension of `/nirs(i)/data(j)/dataTimeSeries`.
+
+#### /nirs(i)/data(j)/measurementLists/dataTypeLabel 
+* **Presence**: optional
+* **Type**:  string 1-D array
+* **Location**: `/nirs(i)/data(j)/measurementLists/dataTypeLabel`
+
+Data-type label. A 1-D array with length equal to the size of the second dimension of `/nirs(i)/data(j)/dataTimeSeries`.
+
+#### /nirs(i)/data(j)/measurementLists/dataTypeIndex 
+* **Presence**: required if measurementLists is present
+* **Type**:  integer 1-D array
+* **Location**: `/nirs(i)/data(j)/measurementLists/dataTypeIndex`
+
+Data-type specific parameter indices. A 1-D array with length equal to the size of the second dimension of `/nirs(i)/data(j)/dataTimeSeries`. Note that the Time Domain and Diffuse Correlation Spectroscopy data types have two additional parameters and so `dataTimeIndex` must be a 2-D array with 2 columns that index the additional parameters.
+
+#### /nirs(i)/data(j)/measurementLists/sourcePower 
+* **Presence**: optional
+* **Type**:  numeric 1-D array
+* **Location**: `/nirs(i)/data(j)/measurementLists/sourcePower`
+
+A 1-D array with length equal to the size of the second dimension of `/nirs(i)/data(j)/dataTimeSeries`. Units are optionally defined in `metaDataTags`.
+
+#### /nirs(i)/data(j)/measurementLists/detectorGain 
+* **Presence**: optional
+* **Type**:  numeric 1-D array
+* **Location**: `/nirs(i)/data(j)/measurementLists/detectorGain`
+
+A 1-D array with length equal to the size of the second dimension of `/nirs(i)/data(j)/dataTimeSeries`. Units are optionally defined in `metaDataTags`.
+
 #### /nirs(i)/stim(j) 
 * **Presence**: optional
 * **Type**:  indexed group
@@ -574,7 +686,7 @@ used to annotate the meanings of each data column.
 
 #### /nirs(i)/stim(j)/dataLabels
 * **Presence**: optional 
-* **Type**:  string array
+* **Type**:  string 1-D array
 * **Location**: `/nirs(i)/stim(j)/dataLabels(k)`
 
 This is a string array providing annotations for each data column in 
@@ -754,7 +866,7 @@ wavelengths>`. This is indexed by `measurementList(k).sourceIndex` and
 
 #### /nirs(i)/probe/detectorLabels 
 * **Presence**: optional 
-* **Type**:  string array
+* **Type**:  string 1-D array
 * **Location**: `/nirs(i)/probe/detectorLabels(j)`
 
 This is a string array providing user friendly or instrument specific labels 
@@ -793,7 +905,7 @@ index to the labels of the given landmark. Label names are stored in the
 
 #### /nirs(i)/probe/landmarkLabels(j) 
 * **Presence**: optional 
-* **Type**:  string array
+* **Type**:  string 1-D array
 * **Location**: `/nirs(i)/probe/landmarkLabels(j)`
 
 This string array stores the names of the landmarks. The first string denotes