diff --git a/src/common-principles.md b/src/common-principles.md
index c3a395c600..fac5eca13b 100644
--- a/src/common-principles.md
+++ b/src/common-principles.md
@@ -85,7 +85,7 @@ saved under a particular filename specified in the standard. This standard
 aspires to describe a majority of datasets, but acknowledges that there will be
 cases that do not fit. In such cases one can include additional files and
 subdirectories to the existing directory structure following common sense. For example
-one may want to include eye tracking data in a vendor specific format that is
+one may want to include eye-tracking data in a vendor specific format that is
 not covered by this standard. The most sensible place to put it is next to the
 continuous recording file with the same naming scheme but different extensions.
 The solutions will change from case to case and publicly available datasets will
diff --git a/src/modality-agnostic-files/events.md b/src/modality-agnostic-files/events.md
index 1c65a0196e..5aa206bce8 100644
--- a/src/modality-agnostic-files/events.md
+++ b/src/modality-agnostic-files/events.md
@@ -264,6 +264,22 @@ and a guide for using macros can be found at
 -->
 {{ MACROS___make_subobject_table("metadata.StimulusPresentation") }}
 
+!!! warning "Important"
+
+    Some metadata of the `StimulusPresentation` object become REQUIRED with the presence of
+    "gaze-on-screen"
+    [eye-tracking data](../modality-specific-files/physiological-recordings.md#eye-tracking),
+    as identified by the `"SampleCoordinateSystem"` metadata.
+
+    The following fields pertaining to `<matches>_events.json` of tasks that were acquired
+    with the simultaneous recording of eye-tracking escalate to REQUIRED as they are considered
+    essential in eye-tracking data analysis:
+
+    -   `StimulusPresentation.ScreenDistance`,
+    -   `StimulusPresentation.ScreenOrigin`,
+    -   `StimulusPresentation.ScreenResolution`,
+    -   `StimulusPresentation.ScreenSize`.
+
 The operating system description SHOULD include the following attributes:
 
 -   type (for example, Windows, macOS, Linux)
diff --git a/src/modality-specific-files/physiological-recordings.md b/src/modality-specific-files/physiological-recordings.md
index 14740b1b6f..fd9c726c92 100644
--- a/src/modality-specific-files/physiological-recordings.md
+++ b/src/modality-specific-files/physiological-recordings.md
@@ -1,10 +1,5 @@
 # Physiological recordings
 
-Physiological recordings such as cardiac and respiratory signals MAY be
-specified using a [compressed tabular file](../common-principles.md#compressed-tabular-files)
-([TSV.GZ file](../glossary.md#tsv_gz-extensions)) and a corresponding
-JSON file for storing metadata fields (see below).
-
 !!! example "Example datasets"
 
       [Example datasets](https://bids-standard.github.io/bids-examples/#dataset-index)
@@ -14,31 +9,130 @@ JSON file for storing metadata fields (see below).
       -   [`7t_trt`](https://github.com/bids-standard/bids-examples/tree/master/7t_trt)
       -   [`ds210`](https://github.com/bids-standard/bids-examples/tree/master/ds210)
 
+## General specifications
+
+Continuous (that is, regularly sampled over time at a fixed frequency)
+physiological recordings such as cardiac and respiratory signals, and
+asynchronous events corresponding to those signals MAY be specified using
+[compressed tabular files](../common-principles.md#compressed-tabular-files)
+([TSV.GZ file](../glossary.md#tsvgz-extensions)).
+TSV.GZ files MUST be accompanied by a JSON file with the same name as their
+corresponding tabular file but with a `.json` extension.
+
 {{ MACROS___make_filename_template(
        "raw",
        placeholders=True,
        show_entities=["recording"],
-       suffixes=["physio"]
+       suffixes=["physio", "physioevents"]
    )
 }}
 
+The [`recording-<label>`](../appendices/entities.md#recording)
+entity is OPTIONAL, and is [described below](#continuous-physiological-recordings).
+
 !!! warning "Caution"
 
-    `<matches>_physio.tsv.gz` files MUST NOT include a header line, as established by the
-    [common-principles](../common-principles.md#compressed-tabular-files).
-    As a result, when supplying a `<matches>_physio.tsv.gz` file, an accompanying
-    `<matches>_physio.json` MUST be present to indicate the column names.
+    Columns of TSV.GZ files MUST be defined in the corresponding JSON sidecar
+    and the tabular content MUST NOT include a header line.
+
+    As a consequence, when supplying a `<matches>_<physio|physioevents>.tsv.gz` file,
+    an accompanying `<matches>_<physio|physioevents>.json` MUST be supplied as well.
+
+For multi-echo data, a single `_physio.<tsv.gz|json>` file without the
+[`echo-<index>`](../appendices/entities.md#echo) entity applies to all echos of
+a particular run.
+For example:
+
+<!-- This block generates a file tree.
+A guide for using macros can be found at
+ https://github.com/bids-standard/bids-specification/blob/master/macros_doc.md
+-->
+{{ MACROS___make_filetree_example({
+  "sub-01": {
+    "func": {
+      "sub-01_task-nback_run-1_echo-1_bold.nii.gz": "",
+      "sub-01_task-nback_run-1_echo-2_bold.nii.gz": "",
+      "sub-01_task-nback_run-1_echo-3_bold.nii.gz": "",
+      "sub-01_task-nback_run-1_physio.tsv.gz": "",
+    },
+  },
+}) }}
+
+This specification section first describes the organization of
+[continuous physiological recordings](#continuous-physiological-recordings), and
+then [events corresponding to the physiological recordings](#physiology-events).
+Finally, the remainder of the document describes
+[specific types of continuous recordings](#specific-physiological-signal-types)
+such as [eye-tracking](#eye-tracking).
+
+## Continuous physiological recordings
+
+Continuous physiological recordings, such as pulse monitoring,
+electrocardiogram, respiratory movement measured with a respiration belt,
+gas concentration, or eye-tracking, MUST use `_physio.<tsv.gz|json>` pairs.
 
+### Storing different recordings
 The [`recording-<label>`](../appendices/entities.md#recording)
 entity MAY be used to distinguish between several recording files.
-For example `sub-01_task-bart_recording-eyetracking_physio.tsv.gz` to contain
-the eyetracking data in a certain sampling frequency, and
-`sub-01_task-bart_recording-breathing_physio.tsv.gz` to contain respiratory
-measurements in a different sampling frequency.
+Recordings with different metadata such as sampling frequencies
+or recording device MUST be stored in separate files with different
+[`recording-<label>`](../appendices/entities.md#recording) entities.
+For example, given a BOLD acquisition of a breath-holding task (`task-bht`)
+for which pulse and respiratory movement were sampled at different frequencies,
+recordings are separated as follows:
+
+<!-- This block generates a file tree.
+A guide for using macros can be found at
+ https://github.com/bids-standard/bids-specification/blob/master/macros_doc.md
+-->
+{{ MACROS___make_filetree_example({
+  "sub-01": {
+    "func": {
+      "sub-01_task-bht_bold.nii.gz": "",
+      "sub-01_task-bht_recording-cardiac_physio.json": "",
+      "sub-01_task-bht_recording-cardiac_physio.tsv.gz": "",
+      "sub-01_task-bht_recording-respiratory_physio.json": "",
+      "sub-01_task-bht_recording-respiratory_physio.tsv.gz": "",
+    },
+  },
+}) }}
+
+**Metadata fields for `<matches>_physio.json` files**.
+General metadata fields include `SamplingFrequency`, `StartTime`, `Columns`,
+and `Manufacturer`, in addition to individual column descriptions.
+Each individual column in the TSV file MAY be documented as its own field in the JSON file
+(identical to the practice in other TSV+JSON file pairs).
+
+!!! warning "Caution"
 
-Physiological recordings (including eyetracking) MUST use the `_physio` suffix.
+    Recordings with different key metadata MUST be split into separate files.
 
-The following tables specify metadata fields for the `*_physio.json` file.
+When key metadata such as sampling frequencies, manufacturers varies between recordings,
+tabular data MUST be split into separate files.
+In such cases, the [`recording-<label>`](../appendices/entities.md#recording)
+entity MUST be used to distinguish these files.
+
+Metadata sidecar files (`<matches>_physio.json`) MAY define the field
+`PhysioType` to indicate a specific type of recording.
+The default value of `PhysioType` is `"generic"`, and MUST be assumed
+if the `PhysioType` metadata is not defined.
+Specific recording types (that is, when `PhysioType` takes a valid value other than `"generic"`)
+have separate prescriptions for columns in the TSV.GZ files and corresponding metadata
+specifications.
+
+!!! tip "RECOMMENDED"
+
+    Using specific recording types is RECOMMENDED when available in the
+    specification.
+
+    The allowed physiological recording types encoded by `PhysioType` and
+    their corresponding metadata specifications are described in subsection
+    [Specific physiological signal types](#specific-physiological-signal-types)
+    below, and its subsections:
+
+    -   eye-tracking ([subsection Eye-tracking](#eye-tracking)).
+
+The following table specifies metadata fields for `"generic"` recordings:
 
 <!-- This block generates a metadata table.
 These tables are defined in
@@ -48,9 +142,10 @@ The definitions of the fields specified in these tables may be found in
 A guide for using macros can be found at
  https://github.com/bids-standard/bids-specification/blob/master/macros_doc.md
 -->
-{{ MACROS___make_sidecar_table(["continuous.Continuous"]) }}
+{{ MACROS___make_sidecar_table(["continuous.Continuous", "continuous.PhysioTypeRecommended"]) }}
 
-## Hardware information
+**Hardware information**.
+Details about the hardware MAY be stored with the following metadata fields.
 
 <!-- This block generates a metadata table.
 These tables are defined in
@@ -66,23 +161,57 @@ Additional metadata may be included as in
 [any TSV file](../common-principles.md#tabular-files) to specify, for
 example, the units of the recorded time series.
 
-Example `*_physio.tsv.gz`:
+**Column naming recommendations for `"generic"` recordings.**
+To store pulse or breathing measurements, or the scanner trigger signal,
+the following naming conventions SHOULD be used for the column names:
 
-<!-- This block generates a file tree.
-A guide for using macros can be found at
+<!-- This block generates a columns table.
+The definitions of these fields can be found in
+  src/schema/rules/tabular_data/*.yaml
+and a guide for using macros can be found at
  https://github.com/bids-standard/bids-specification/blob/master/macros_doc.md
 -->
-{{ MACROS___make_filetree_example(
+{{ MACROS___make_columns_table("physio.PhysioColumns") }}
+
+Please note that the specification of columns such as `cardiac`, `respiratory`, and `trigger` above
+follow the general specifications for [tabular files](../common-principles.md#tabular-files):
+
+<!-- This table should be the same as that in the common-principles.md file,
+	   unless the specification wants to specifically deviate for physio at some point.
+-->
+{{ MACROS___make_metadata_table(
    {
-   "sub-control01": {
-      "func": {
-         "sub-control01_task-nback_physio.tsv.gz": "",
-         },
-      },
+        "LongName": "OPTIONAL",
+        "Description": (
+            "RECOMMENDED",
+            "The description of the column.",
+        ),
+        "Levels": "RECOMMENDED",
+        "Units": "RECOMMENDED",
+        "Delimiter": "OPTIONAL",
+        "TermURL": "RECOMMENDED",
+        "HED": "OPTIONAL",
    }
 ) }}
 
-(after decompression)
+**Examples**.
+Let's encode cardiac and respiratory recordings, as well as a trigger signal,
+the three of them sampled at 100.0 Hz by the same device during a behavioral task:
+<!-- This block generates a file tree.
+A guide for using macros can be found at
+ https://github.com/bids-standard/bids-specification/blob/master/macros_doc.md
+-->
+{{ MACROS___make_filetree_example({
+  "sub-01": {
+    "func": {
+      "sub-01_task-nback_physio.json": "",
+      "sub-01_task-nback_physio.tsv.gz": "",
+    },
+  },
+}) }}
+
+In this example, the contents of `sub-01_task-nback_physio.tsv.gz`
+after decompression are:
 
 ```tsvgz {linenums="1"}
 34	110	0
@@ -90,94 +219,520 @@ A guide for using macros can be found at
 23	100	1
 ```
 
-Example `*_physio.json`:
+and the header-less TSV.GZ contents are described with the following
+metadata `sub-01_task-nback_physio.json` where the `Columns` field defines
+the names corresponding to the three columns above:
+
+```JSON
+{
+    "Columns": ["cardiac", "respiratory", "trigger"],
+    "Manufacturer": "Brain Research Equipment ltd.",
+    "PhysioType": "generic",
+    "SamplingFrequency": 100.0,
+    "StartTime": -22.345,
+    "cardiac": {
+      "Description": "continuous pulse measurement",
+      "Units": "mV"
+    },
+    "respiratory": {
+      "Description": "continuous measurements by respiration belt",
+      "Units": "mV"
+    },
+    "trigger": {
+      "Description": "continuous measurement of the scanner trigger signal",
+      "Units": "V"
+    }
+}
+```
+
+The example shows the three REQUIRED metadata entries `Columns`, `SamplingFrequency`,
+and `StartTime`.
+Columns are further described following the specifications for
+[tabular files](../common-principles.md#tabular-files),
+indicating `Description` and `Units` fields.
+Other fields, such as `TermURL`, `LongName`, MAY be included.
+
+Because a missing `PhysioType` is assumed to be `"generic"`, the following sidecar is equivalent:
+
+```JSON
+{
+    "Columns": ["cardiac", "respiratory", "trigger"],
+    "Manufacturer": "Brain Research Equipment ltd.",
+    "SamplingFrequency": 100.0,
+    "StartTime": -22.345,
+    "cardiac": {
+      "Description": "continuous pulse measurement",
+      "Units": "mV"
+    },
+    "respiratory": {
+      "Description": "continuous measurements by respiration belt",
+      "Units": "mV"
+    },
+    "trigger": {
+      "Description": "continuous measurement of the scanner trigger signal",
+      "Units": "V"
+    }
+}
+```
+
+If the `"cardiac"` and `"respiratory"` signals above were acquired at different
+sampling frequencies, then the recordings MUST be separated into two files
+disambiguated by the [`recording-<label>`](../appendices/entities.md#recording)
+entity:
 
 <!-- This block generates a file tree.
 A guide for using macros can be found at
  https://github.com/bids-standard/bids-specification/blob/master/macros_doc.md
 -->
-{{ MACROS___make_filetree_example(
-   {
-   "sub-control01": {
-      "func": {
-         "sub-control01_task-nback_physio.json": "",
-         },
-      },
-   }
-) }}
+{{ MACROS___make_filetree_example({
+  "sub-01": {
+    "func": {
+      "sub-01_task-nback_recording-cardiac_physio.json": "",
+      "sub-01_task-nback_recording-cardiac_physio.tsv.gz": "",
+      "sub-01_task-nback_recording-respiratory_physio.json": "",
+      "sub-01_task-nback_recording-respiratory_physio.tsv.gz": "",
+    },
+  },
+}) }}
+
+## Physiology "events"
+
+Discontinuous data associated with continuous recordings
+stored in `<matches>_physio.tsv.gz` files MAY be specified
+following the summary template pattern above.
+
+Physiology "events" files `<matches>_recording-<label>_physioevents.tsv.gz`
+MUST follow specific column specifications:
+
+<!--
+This block generates a columns table.
+The definitions of these fields can be found in
+  src/schema/rules/tabular_data/physio.yaml
+and a guide for using macros can be found at
+ https://github.com/bids-standard/bids-specification/blob/master/macros_doc.md
+-->
+{{ MACROS___make_columns_table("physio.PhysioEventsColumns") }}
+
+The following table specifies metadata fields for the
+`<matches>[_recording-<label>]_physioevents.json` file.
+
+<!-- This block generates a metadata table.
+These tables are defined in
+  src/schema/rules/sidecars
+The definitions of the fields specified in these tables may be found in
+  src/schema/objects/metadata.yaml
+A guide for using macros can be found at
+ https://github.com/bids-standard/bids-specification/blob/master/macros_doc.md
+-->
+{{ MACROS___make_sidecar_table(["continuous.PhysioEvents"]) }}
+
+The REQUIRED `OnsetSource` metadata specifies the interpretation of
+the values of the `onset` column.
+If `OnsetSource` is the name of a column in the associated
+`<matches>[_recording-<label>]_physio.tsv.gz` file, the values have the same interpretation
+as values in the named column.
+
+For example, considering the following structure:
+
+<!-- This block generates a file tree.
+A guide for using macros can be found at
+ https://github.com/bids-standard/bids-specification/blob/master/macros_doc.md
+-->
+{{ MACROS___make_filetree_example({
+  "sub-01": {
+    "func": {
+      "sub-01_task-nback_physio.json": "",
+      "sub-01_task-nback_physio.tsv.gz": "",
+      "sub-01_task-nback_physioevents.json": "",
+      "sub-01_task-nback_physioevents.tsv.gz": "",
+    },
+  },
+}) }}
+
+The decompressed contents of `sub-01_task-nback_physio.tsv.gz` are:
+
+```{.text noheader="1" linenums="1"}
+13894432329	10.1
+13894432330	10.0
+13894432331     9.5
+13894432332     9.2
+13894432333     9.0
+13894432334	10.2
+13894432335	10.3
+13894432336	10.1
+```
+
+And `sub-01_task-nback_physio.json` defines `timestamp` column:
 
 ```JSON
 {
     "SamplingFrequency": 100.0,
     "StartTime": -22.345,
-    "Columns": ["cardiac", "respiratory", "trigger"],
-    "Manufacturer": "Brain Research Equipment ltd.",
+    "Columns": ["timestamp", "cardiac"],
     "cardiac": {
         "Description": "continuous pulse measurement",
         "Units": "mV"
-        },
-    "respiratory": {
-        "Description": "continuous measurements by respiration belt",
-        "Units": "mV"
-        },
-    "trigger": {
-        "Description": "continuous measurement of the scanner trigger signal"
-        }
+    },
+    "timestamp": {
+        "Description": "a continuously increasing identifier of the sampling time registered by the device",
+        "Units": "ms",
+        "Origin": "System startup"
+    }
 }
 ```
 
-Note how apart from the general metadata fields like `SamplingFrequency`, `StartTime`, `Columns`,
-and `Manufacturer`,
-each individual column in the TSV file may be documented as its own field in the JSON file
-(identical to the practice in other TSV+JSON file pairs).
-Here, only the `Description` and `Units` fields are shown, but you may use any other of the
-[defined fields](../common-principles.md#tabular-files) such as `TermURL`, `LongName`, and so on.
-In this example, the `"cardiac"` and `"respiratory"` time series are produced by devices from
-the same manufacturer and follow the same sampling frequency.
-To specify different sampling frequencies or manufacturers, the time series would have to be split
-into separate files like `*_recording-cardiac_physio.<tsv.gz|json>` and `*_recording-respiratory_physio.<tsv.gz|json>`.
+The decompressed contents of the corresponding `sub-01_task-nback_physioevents.tsv.gz` are:
 
-## Recommendations for specific use cases
+```{.text noheader="1" linenums="1"}
+13894432325	Ready
+13894432331	Synchronous recalibration triggered
+13894432334	External message received: new block
+```
 
-To store pulse or breathing measurements, or the scanner trigger signal, the
-following naming conventions SHOULD be used for the column names:
+To indicate that the first column (`onset`) is to be interpreted as a timestamp,
+the `OnsetSource` MUST be set to `"timestamp"` in `sub-01_task-nback_physioevents.json`:
 
-<!-- This block generates a columns table.
+```JSON
+{
+    "Columns": ["onset", "message"],
+    "Description": "Messages logged by the measurement device",
+    "OnsetSource": "timestamp"
+}
+```
+
+If there is no appropriate source column in
+`<matches>[_recording-<label>]_physio.tsv.gz`, `OnsetSource` MAY be set to `"n/a"`.
+In this case, the values of `onset` MUST be interpreted as row indices
+into the `physio` file, with the first row having index zero (`0`).
+Negative onsets are possible, and such events are interpreted as occurring prior
+to the start of the recording, at the same sampling rate.
+
+For example, the above `sub-01_task-nback_physioevents.tsv.gz` could be equivalently
+written:
+
+```{.text noheader="1"}
+-3	Ready
+3	Synchronous recalibration triggered
+6	External message received: new block
+```
+
+To indicate that the first column (`onset`) is to be interpreted as an index,
+the `OnsetSource` is set to `"n/a"` in `sub-01_task-nback_physioevents.json`:
+
+```JSON
+{
+    "Columns": ["onset", "message"],
+    "Description": "Messages logged by the measurement device",
+    "OnsetSource": "n/a"
+}
+```
+
+## Specific physiological signal types
+
+### Eye-tracking
+
+<!--
+1. Datasets will be updated later to adapt to the agreed format.
+2. We aim at adding a last example converting published dataset from openeuro.
+-->
+!!! example "Example datasets"
+
+    [Example datasets](https://bids-standard.github.io/bids-examples/#dataset-index)
+    with eye-tracking data have been formatted using this specification
+    and can be used for practical guidance when curating a new dataset:
+
+    -   Combined fMRI and eye-tracking data in a resting-state task, measured with
+        an Eyelink (SR research). Human participant kept their gaze steady at the
+        screen center.
+
+        [BIDS dataset](https://openneuro.org/datasets/ds004158)
+
+    -   Combined behavioral and eye-tracking data, measured with and Eyelink
+        (SR Research). Human participants freely viewed as set of natural images.
+        Published paper: https://doi.org/10.1523/ENEURO.0287-23.2023
+
+        [BIDS dataset](https://github.com/julia-pfarr/natImSac_BIDSexample)
+
+Setting `PhysioType` to the keyword `"eyetrack"` specifies that
+the physiological recordings in the `<matches>_physio.tsv.gz` have
+been acquired with an *eye-tracker*.
+In the following, *eye-tracker* refers to the apparatus allowing
+the recording of gaze position, and, optionally, pupil size.
+
+Eye-tracking data MUST be stored following the general specifications
+for `"generic"` physiological recordings.
+However, it is REQUIRED that recordings corresponding to each eye
+(and/or *cyclopean* or averaged signals for binocular eye-trackers providing
+a third recording) are split into files with different
+[`recording-<label>`](../appendices/entities.md#recording).
+Therefore, the use of [`recording-<label>`](../appendices/entities.md#recording)
+is REQUIRED with eye-tracking data.
+The values `"eye1"`, `"eye2"`, and `"eye3"` are RECOMMENDED as the respective labels
+for the [`recording-<label>`](../appendices/entities.md#recording) entity.
+
+!!! danger "MANDATORY metadata"
+
+    The correspondence of labels and the recorded eye MUST be encoded
+    by the MANDATORY `RecordedEye` metadata.
+
+    The [`recording-<label>`](../appendices/entities.md#recording) entity
+    MAY take other values such as `"left"`, `"cyclopean"`, or `"right"` corresponding
+    to the `RecordedEye` metadata.
+    However, it is RECOMMENDED that metadata is not encoded in the file names to avoid
+    conflicts between filenames and metadata.
+    For example, if [`recording-<label>`](../appendices/entities.md#recording) takes
+    the value `"left"` but the corresponding sidecar JSON file contains a definition of
+    `RecordedEye` being `"right"`.
+
+Eye-tracking files `<matches>_recording-<label>_physio.tsv.gz` MUST follow
+specific column prescriptions:
+
+<!--
+This block generates a columns table.
 The definitions of these fields can be found in
-  src/schema/rules/tabular_data/*.yaml
+  src/schema/rules/tabular_data/eyetrack.yaml
 and a guide for using macros can be found at
  https://github.com/bids-standard/bids-specification/blob/master/macros_doc.md
 -->
-{{ MACROS___make_columns_table("physio.PhysioColumns") }}
+{{ MACROS___make_columns_table("physio.PhysioEyeTracking") }}
+
+Please note that the specification of columns such as `timestamp`, `x_coordinate`, `y_coordinate`, and `pupil_size`
+follow the general specifications for [tabular files](../common-principles.md#tabular-files) and MAY define
+metadata fields such as [`LongName`](../glossary.md#objects.metadata.LongName),
+[`Description`](../glossary.md#objects.metadata.Description),
+[`Levels`](../glossary.md#objects.metadata.Levels), or
+[`TermURL`](../glossary.md#objects.metadata.TermURL).
+However, in the case of eye-tracking, the metadata entry [`Units`](../glossary.md#objects.metadata.Units),
+becomes REQUIRED for the columns `x_coordinate` and `y_coordinate`:
+
+{{ MACROS___make_metadata_table(
+   {
+        "Units": "REQUIRED",
+   }
+) }}
 
-For any other data to be specified in columns, the column names can be chosen
-as deemed appropriate by the researcher.
+The following table specifies metadata fields for the
+`<matches>_recording-<label>_physio.json` file:
 
-Recordings with different sampling frequencies or starting times should be
-stored in separate files
-(and the [`recording-<label>`](../appendices/entities.md#recording)
-entity MAY be used to distinguish these files).
+<!-- This block generates a metadata table.
+These tables are defined in
+  src/schema/rules/sidecars
+The definitions of the fields specified in these tables may be found in
+  src/schema/objects/metadata.yaml
+A guide for using macros can be found at
+ https://github.com/bids-standard/bids-specification/blob/master/macros_doc.md
+-->
+{{ MACROS___make_sidecar_table([
+    "continuous.Continuous",
+    "continuous.PhysioHardware",
+    "continuous.PhysioTypeRequired",
+    "continuous.EyeTrack"
+]) }}
 
-For motion parameters acquired from MRI scanner side motion correction, the
-`_physio` suffix MUST be used.
+Comprehensively documenting the calibration metadata is RECOMMENDED.
 
-For multi-echo data, a given `physio.tsv` file is applicable to all echos of
-a particular run.
-For example:
+Eye-tracking files `<matches>_recording-<label>_physio.tsv.gz` MAY be annotated
+with a corresponding `<matches>_recording-<label>_physioevents.tsv.gz` file.
+The `<matches>_recording-<label>_physioevents.tsv.gz` file MAY be employed to
+record discontinuous model parameters generated by the eye-tracker, for example,
+those derived from the saccade and blinks model some eye-trackers produce.
 
+!!! warning "Important"
+
+    For eye-tracking recordings where `"SampleCoordinateSystem"` is set to `"gaze-on-screen"`,
+    the following fields pertaining to `<matches>_events.json` escalate to REQUIRED
+    as they are considered essential in eye-tracking data analysis:
+
+    -   `StimulusPresentation.ScreenDistance`,
+    -   `StimulusPresentation.ScreenOrigin`,
+    -   `StimulusPresentation.ScreenResolution`,
+    -   `StimulusPresentation.ScreenSize`.
+
+**Examples**.
+The recordings produced by a monocular eye-tracker during a
+visual search task may display the following structure:
 <!-- This block generates a file tree.
 A guide for using macros can be found at
  https://github.com/bids-standard/bids-specification/blob/master/macros_doc.md
 -->
-{{ MACROS___make_filetree_example(
-   {
-   "sub-01": {
-      "func": {
-        "sub-01_task-cuedSGT_run-1_physio.tsv.gz": "",
-        "sub-01_task-cuedSGT_run-1_echo-1_bold.nii.gz": "",
-        "sub-01_task-cuedSGT_run-1_echo-2_bold.nii.gz": "",
-        "sub-01_task-cuedSGT_run-1_echo-3_bold.nii.gz": "",
-         },
-      },
+{{ MACROS___make_filetree_example({
+  "sub-01": {
+    "func": {
+      "sub-01_task-visualSearch_bold.json": "",
+      "sub-01_task-visualSearch_bold.nii.gz": "",
+      "sub-01_task-visualSearch_events.json": "",
+      "sub-01_task-visualSearch_events.tsv": "",
+      "sub-01_task-visualSearch_recording-eye1_physio.json": "",
+      "sub-01_task-visualSearch_recording-eye1_physio.tsv.gz": "",
+      "sub-01_task-visualSearch_recording-eye1_physioevents.json": "",
+      "sub-01_task-visualSearch_recording-eye1_physioevents.tsv.gz": ""
+    },
+  },
+}) }}
+
+The above example is extended to a binocular eye-tracker producing three signals
+(left and right eyes, plus a *cyclopean* recording), as follows:
+<!-- This block generates a file tree.
+A guide for using macros can be found at
+ https://github.com/bids-standard/bids-specification/blob/master/macros_doc.md
+-->
+{{ MACROS___make_filetree_example({
+  "sub-01": {
+    "func": {
+      "sub-01_task-visualSearch_bold.json": "",
+      "sub-01_task-visualSearch_bold.nii.gz": "",
+      "sub-01_task-visualSearch_events.json": "",
+      "sub-01_task-visualSearch_events.tsv": "",
+      "sub-01_task-visualSearch_recording-eye1_physio.json": "",
+      "sub-01_task-visualSearch_recording-eye1_physio.tsv.gz": "",
+      "sub-01_task-visualSearch_recording-eye1_physioevents.json": "",
+      "sub-01_task-visualSearch_recording-eye1_physioevents.tsv.gz": "",
+      "sub-01_task-visualSearch_recording-eye2_physio.json": "",
+      "sub-01_task-visualSearch_recording-eye2_physio.tsv.gz": "",
+      "sub-01_task-visualSearch_recording-eye2_physioevents.json": "",
+      "sub-01_task-visualSearch_recording-eye2_physioevents.tsv.gz": "",
+      "sub-01_task-visualSearch_recording-eye3_physio.json": "",
+      "sub-01_task-visualSearch_recording-eye3_physio.tsv.gz": "",
+      "sub-01_task-visualSearch_recording-eye3_physioevents.json": "",
+      "sub-01_task-visualSearch_recording-eye3_physioevents.tsv.gz": ""
+    },
+  },
+}) }}
+
+Given the above example file structures, a corresponding
+`sub-01_task-visualSearch_recording-eye1_physio.json` sidecar
+could read:
+
+```JSON
+{
+    "DeviceSerialNumber": "17535483",
+    "Columns": ["timestamp", "x_coordinate", "y_coordinate", "pupil_size"],
+    "Manufacturer": "SR-Research",
+    "ManufacturersModelName": "EYELINK II CL v4.56 Aug 18 2010",
+    "PhysioType": "eyetrack",
+    "RecordedEye": "right",
+    "SampleCoordinateSystem": "gaze-on-screen",
+    "SamplingFrequency": 1000,
+    "SoftwareVersion": "SREB1.10.1630 WIN32 LID:F2AE011 Mod:2017.04.21 15:19 CEST",
+    "ScreenAOIDefinition": [
+        "square",
+        [100, 150, 300, 350]
+    ],
+    "timestamp": {
+        "Description": "a continuously increasing identifier of the sampling time registered by the device",
+        "Units": "ms",
+        "Origin": "System startup"
+    },
+    "x_coordinate": {
+      "LongName": "Gaze position (x)",
+      "Description": "Gaze position x-coordinate of the recorded eye, in the coordinate units specified in the corresponding metadata sidecar.",
+      "Units": "pixel"
+    },
+    "y_coordinate": {
+      "LongName": "Gaze position (y)",
+      "Description": "Gaze position y-coordinate of the recorded eye, in the coordinate units specified in the corresponding metadata sidecar.",
+      "Units": "pixel"
+    },
+    "pupil_size": {
+        "Description": "Pupil area of the recorded eye as calculated by the eye-tracker in arbitrary units (see EyeLink's documentation for conversion).",
+        "Units": "arbitrary"
+    }
+}
+```
+
+Content of `sub-01_task-VisualSearch_events.json`:
+
+```JSON
+{
+   "TaskName": "Visual Search",
+   "InstitutionName": "Stanford University",
+   "InstitutionAddress": "450 Serra Mall, Stanford, CA 94305-2004, USA",
+   "StimulusPresentation": {
+       "ScreenDistance": 0.6,
+       "ScreenOrigin": ["top", "left"],
+       "ScreenRefreshRate": 60,
+       "ScreenResolution": [1024, 768],
+       "ScreenSize": [0.386, 0.29]
    }
-) }}
+}
+```
+
+**Example eye-tracking recording**.
+Given the above `sub-01_task-visualSearch_recording-eye1_physio.json` metadata
+specification, the decompressed content of the
+`sub-01_task-visualSearch_recording-eye1_physio.tsv.gz` can be:
+
+```TSV
+7186799    416.29    267.39    4612.0
+7186800    416.29    268.10    4623.0
+7186801    416.20    269.00    4623.0
+7186802    415.89    269.60    4613.0
+7186803    415.70    269.20    4603.0
+7186804    415.60    266.79    4591.0
+7186805    415.79    264.60    4589.0
+7186806    416.10    263.89    4587.0
+7186807    416.29    265.20    4587.0
+7186808    416.39    266.50    4588.0
+7186809    416.50    266.79    4594.0
+7186810    416.50    267.20    4599.0
+7186811    416.10    268.00    4609.0
+7186812    415.70    268.29    4612.0
+7186813    416.00    268.60    4605.0
+```
+
+Example `sub-01_task-visualSearch_recording-eye1_physioevents.tsv.gz` corresponding
+to the above eye-tracking recording, after decompressing:
+
+```TSV
+7184392    n/a    n/a         n/a    "NO Reply is disabled for function eyelink_cal_result"
+7184392    n/a    n/a         n/a    "RECCFG CR 1000 2 0 R"
+7184392    n/a    n/a         n/a    "ELCLCFG TOWER"
+7186771    n/a    n/a         n/a    "First task trigger"
+7186806    72     fixation    0      n/a
+7186879    231    saccade     1      n/a
+7187111    6186   fixation    0      n/a
+7193298    216    saccade     1      n/a
+7193515    1286   fixation    0      n/a
+7194802    24     saccade     0      n/a
+7194827    2403   fixation    0      n/a
+7197231    17     saccade     0      n/a
+7197249    1640   fixation    0      n/a
+7198890    6      saccade     0      n/a
+7198897    1105   fixation    0      n/a
+7200003    233    saccade     1      n/a
+7200237    184    fixation    0      n/a
+7200422    15     saccade     0      n/a
+7200438    264    fixation    0      n/a
+```
+
+where the first three rows are logged by the eye-tracker and the fourth row shows
+a *message* asynchronously received by the eye-tracker.
+The remainder of the rows contain a subset of parameters registered by the device,
+derived from applying a model to identify saccades and blinks.
+The corresponding `sub-01_task-visualSearch_recording-eye1_physioevents.json` sidecar
+would read:
+
+```JSON
+{
+    "Columns": ["onset", "duration", "trial_type", "blink", "message"],
+    "Description": "Messages logged by the measurement device",
+    "OnsetSource": "timestamp",
+    "blink": {
+      "Description": "Gives status of the eye.",
+      "Levels": {
+          "0": "Indicates if the eye was open.",
+          "1": "Indicates if the eye was closed.",
+      },
+    },
+    "message": {
+      "Description": "String messages logged by the eye-tracker."
+    },
+    "trial_type": {
+      "Description": "Event type as identified by the eye-tracker's model.",
+      "Levels": {
+          "fixation": "Indicates a fixation.",
+          "saccade": "Indicates a saccade.",
+      },
+    }
+}
+```
diff --git a/src/schema/meta/associations.yaml b/src/schema/meta/associations.yaml
index ddceeddc4f..08b88e04e6 100644
--- a/src/schema/meta/associations.yaml
+++ b/src/schema/meta/associations.yaml
@@ -14,7 +14,6 @@
 ---
 events:
   selectors:
-    - '"task" in entities'
     - extension != '.json'
   target:
     suffix: events
@@ -101,3 +100,11 @@ electrodes:
     entities:
       - space
   inherit: true
+
+physio:
+  selectors:
+    - extension != '.json'
+  target:
+    suffix: physio
+    extension: .tsv.gz
+  inherit: false
diff --git a/src/schema/meta/context.yaml b/src/schema/meta/context.yaml
index bc61dd1cb2..14a288dfcb 100644
--- a/src/schema/meta/context.yaml
+++ b/src/schema/meta/context.yaml
@@ -156,6 +156,9 @@ properties:
             type: array
             items:
               type: string
+          sidecar:
+            description: 'Sidecar metadata constructed via the inheritance principle'
+            type: object
       aslcontext:
         description: 'ASL context file'
         type: object
@@ -277,6 +280,17 @@ properties:
           path:
             description: 'Path to associated coordsystem file'
             type: string
+      physio:
+        description: 'Physiological recording file'
+        type: object
+        required: [path]
+        properties:
+          path:
+            description: 'Path to associated physio file'
+            type: string
+          sidecar:
+            description: 'Sidecar metadata constructed via the inheritance principle'
+            type: object
   # The following properties are populated if the current file is of an appropriate type
   columns:
     description: 'TSV columns, indexed by column header, values are arrays with column contents'
diff --git a/src/schema/objects/columns.yaml b/src/schema/objects/columns.yaml
index f5422abab2..0d48048166 100644
--- a/src/schema/objects/columns.yaml
+++ b/src/schema/objects/columns.yaml
@@ -164,6 +164,37 @@ duration:
   type: number
   unit: s
   minimum: 0
+x_coordinate:
+  name: x_coordinate
+  display_name: Gaze x-coordinate
+  description: |
+    Gaze position x-coordinate of the recorded eye, in the coordinate
+    units specified in the corresponding metadata sidecar.
+  type: number
+y_coordinate:
+  name: y_coordinate
+  display_name: Gaze y-coordinate
+  description: |
+    Gaze position y-coordinate of the recorded eye, in the coordinate
+    units specified in the corresponding metadata sidecar.
+  type: number
+pupil_size:
+  name: pupil_size
+  display_name: Pupil size
+  description: |
+    Pupil size or area of the recorded eye, in the
+    units specified in the corresponding metadata sidecar.
+    It is RECOMMENDED to indicate the particular type of pupil size that is
+    being recorded in the `Description` field of this column.
+    It is RECOMMENDED to specify the `Units` field corresponding to this column.
+  type: number
+timestamp__eyetrack:
+  name: timestamp
+  display_name: Eye-tracking recording timestamp
+  description: |
+    Timestamp issued by the eye-tracker indexing the continuous recordings corresponding to
+    the sampled eye.
+  type: number
 filename:
   name: filename
   display_name: Filename
@@ -274,6 +305,13 @@ mapping:
   description: |
     Corresponding integer label in the standard BIDS label lookup.
   type: integer
+message:
+  name: message
+  display_name: Message
+  description: |
+    Brief free-text description of a message (for example in a log generated
+    by a device), or other information of interest.
+  type: string
 material:
   name: material
   display_name: Electrode material
@@ -374,6 +412,15 @@ participant_id:
     matching a participant entity found in the dataset.
   type: string
   pattern: ^sub-[0-9a-zA-Z+]+$
+onset__physioevents:
+  name: onset
+  display_name: Onset of events in physiological recordings
+  description: |
+    Onset of the event relative to the timeline defined by the corresponding
+    physiological recording file.
+
+    Typically, it will correspond to a timestamp issued by the recording device.
+  type: number
 placement__motion:
   name: placement
   display_name: Placement
diff --git a/src/schema/objects/enums.yaml b/src/schema/objects/enums.yaml
index 19e0e30307..4ea113bc39 100644
--- a/src/schema/objects/enums.yaml
+++ b/src/schema/objects/enums.yaml
@@ -1452,3 +1452,13 @@ microvascular:
   display_name: microvascular
   description: |
     The origin of a tissue: microvascular
+PhysioTypeGeneric:
+  value: generic
+  display_name: Generic Physiological Recording
+  description: |
+    Unspecified physiological recording.
+PhysioTypeEyetrack:
+  value: eyetrack
+  display_name: Eye-tracking recording
+  description: |
+    A specific physiological recording type: eye-tracking.
diff --git a/src/schema/objects/metadata.yaml b/src/schema/objects/metadata.yaml
index e6567a57f5..e54326c215 100644
--- a/src/schema/objects/metadata.yaml
+++ b/src/schema/objects/metadata.yaml
@@ -211,6 +211,13 @@ Authors:
   type: array
   items:
     type: string
+AverageCalibrationError:
+  name: AverageCalibrationError
+  display_name: Average Calibration Error
+  description: |
+    Average calibration error in degrees of visual angle.
+  type: number
+  unit: degree
 B0FieldIdentifier:
   name: B0FieldIdentifier
   display_name: B0 Field Identifier
@@ -385,6 +392,46 @@ BrainLocation:
     or layer to refer to layer-specific gene expression,
     which can also tie up with laminar fMRI.
   type: string
+CalibrationCount:
+  name: CalibrationCount
+  display_name: Calibration Count
+  description: |
+    The number of calibrations corresponding to this run.
+  type: integer
+  minimum: 0
+CalibrationPosition:
+  name: CalibrationPosition
+  display_name: Calibration Position
+  description: |
+    A list of `[x, y]` coordinates in the `CalibrationUnit`.
+    For example, using 5 positions calibration presented on an HD screen,
+    it could be `[[960,50],[960,540],[960,1030],[50,540],[1870,540]]`.
+  type: array
+  items:
+    type: array
+    minItems: 2
+    maxItems: 2
+    items:
+      type: number
+CalibrationType:
+  name: CalibrationType
+  display_name: Calibration Type
+  description: |
+    The type of the calibration procedure executed last.
+    For example the `"H3"` for horizontal calibration with 3 positions
+    or `"HV9"` for horizontal and vertical calibration with 9 positions,
+    or one point calibration.
+  type: string
+CalibrationUnit:
+  name: CalibrationUnit
+  display_name: Calibration Unit
+  description: |
+    Unit of `"CalibrationPosition"`.
+  type: string
+  enum:
+    - pixel
+    - mm
+    - cm
 CASLType:
   name: CASLType
   display_name: CASL Type
@@ -1207,6 +1254,62 @@ EthicsApprovals:
   type: array
   items:
     type: string
+EventIdentifier:
+  name: EventIdentifier
+  display_name: Event Identifier
+  description: |
+    The message sent to the eye-tracker which disambiguates the belonging
+    of the sample to a certain event, condition or group.
+    This can be a unique trial identifier, or in the case of
+    continuous presentation (for example video) the annotated event of interest.
+  type: string
+EyeCameraSettings:
+  name: EyeCameraSettings
+  display_name: Eye Camera Settings
+  description: |
+    A field to store any settings that influence the resolution
+    and quality of the eye imagery.
+    For example, `{"Autowhitebalance": true}`.
+  type: object
+  items:
+    type: object
+EyeTrackerDistance:
+  name: EyeTrackerDistance
+  display_name: Eye-Tracker Distance
+  description: |
+    Distance (in meters) between the eye-tracker and the participant eye(s).
+    Distance can either be expressed as a single numeric value indicating the shortest distance
+    between the participant's eye and the eye-tracker's camera, or a three-coordinates array
+    indicating the X, Y, Z distances between the participant's eye and the eye-tracker's
+    camera.
+  anyOf:
+    - type: number
+      unit: m
+    - type: array
+      items:
+        type: number
+        unit: m
+      minItems: 3
+      maxItems: 3
+EyeTrackingMethod:
+  name: EyeTrackingMethod
+  display_name: Eye-Tracking Method
+  description: |
+    Method used to track gaze or pupil position:
+    "P–CR" for video based eye-tracking using pupil and corneal reflection;
+    "DPI" for Dual-Purkinje Imaging system, "SSC" for scleral search coils;
+    "EOG" for electro-oculogram; "Limbus" for trackers estimating limbus borders
+    between the iris and sclera; or other.
+  type: string
+FeatureDetectionSettings:
+  name: FeatureDetectionSettings
+  display_name: Feature Detection Settings
+  description: |
+    Description of feature detection settings.
+    For example, minimum/maximum pupil size.
+  type: object
+  items:
+    type: object
 FiducialsCoordinateSystem:
   name: FiducialsCoordinateSystem
   display_name: Fiducials Coordinate System
@@ -1292,6 +1395,14 @@ FlipAngle:
         unit: degree
         exclusiveMinimum: 0
         maximum: 360
+OnsetSource:
+  name: OnsetSource
+  display_name: Column Name of the Onset Source
+  description: |
+    An existing column name in an corresponding recoding data TSV file that
+    indexes or is correspondent to the `"onset"` column of the present TSV file.
+    For example, `"timestamp"` column.
+  type: string
 Format:
   name: Format
   display_name: Value format
@@ -1374,6 +1485,15 @@ Funding:
   type: array
   items:
     type: string
+GazeMappingSettings:
+  name: GazeMappingSettings
+  display_name: Gaze Mapping Settings
+  description: |
+    Description of gaze-mapping settings.
+    For example, threshold on pupil confidence required for gaze mapping.
+  type: object
+  items:
+    type: object
 GeneratedBy:
   name: GeneratedBy
   display_name: Generated By
@@ -2239,6 +2359,13 @@ MaxMovement:
     as measured by the head localization coils (for example, `4.8`).
   type: number
   unit: mm
+MaximalCalibrationError:
+  name: MaximalCalibrationError
+  display_name: Maximal Calibration Error
+  description: |
+    Maximal calibration error in degrees of visual angle.
+  type: number
+  unit: degree
 Maximum:
   name: Maximum
   display_name: Maximum value
@@ -2715,6 +2842,16 @@ PhotoDescription:
   description: |
     Description of the photo.
   type: string
+PhysioType:
+  name: PhysioType
+  display_name: Physiological Recording Type
+  description: |
+    Defines the specific type of physiological recording.
+    For backwards compatibility, the default value is `"generic"`.
+  type: string
+  enum:
+    - $ref: objects.enums.PhysioTypeGeneric.value
+    - $ref: objects.enums.PhysioTypeEyetrack.value
 PixelSize:
   name: PixelSize
   display_name: Pixel Size
@@ -2865,6 +3002,15 @@ PulseSequenceType:
   description: |
     A general description of the pulse sequence used for the scan.
   type: string
+PupilFitMethod:
+  name: PupilFitMethod
+  display_name: Pupil Fit Method
+  description: |
+    The method employed for fitting the pupil, for example
+    `"centre-of-mass"` or `"ellipse"`.
+    If `"centre-of-mass"` or `"ellipse"` method is used, it is RECOMMENDED to
+    use these exact labels.
+  type: string
 Purity:
   name: Purity
   display_name: Purity
@@ -2881,6 +3027,12 @@ RandomRate:
   type: array
   items:
     type: number
+RawDataFilters:
+  name: RawDataFilters
+  display_name: Raw Data Filters
+  description: |
+    Filter settings applied to eye-movement raw data.
+  type: string
 RawSources:
   name: RawSources
   display_name: Raw Sources
@@ -2983,6 +3135,18 @@ ReconMethodParameterValues:
   type: array
   items:
     type: number
+RecordedEye:
+  name: RecordedEye
+  display_name: Recorded Eye
+  description: |
+    Indicates the eye tracked, for example, `"left"` or `"right"`.
+    It SHOULD be set to `"cyclopean"` for recordings combining both eyes
+    as potentially generated by binocular eye-trackers.
+  type: string
+  enum:
+    - left
+    - right
+    - cyclopean
 RecordingDuration:
   name: RecordingDuration
   display_name: Recording Duration
@@ -3153,6 +3317,22 @@ SEEGChannelCount:
     Number of SEEG channels.
   type: integer
   minimum: 0
+SampleCoordinateSystem:
+  name: SampleCoordinateSystem
+  display_name: Coordinate System of the Gaze Position
+  description: |
+    Coordinate system of the gaze position recordings.
+    Generally eye-trackers are set to use `"gaze-on-screen"` coordinate system, but you may use
+    `"eye-in-head"` or `"gaze-in-world"`.
+    If none of the three default options properly describe the coordinate system, the
+    `"custom"` keyword MUST be employed and the coordinate system MUST be described
+    using additional metadata entries.
+  type: string
+  enum:
+    - gaze-on-screen
+    - eye-in-head
+    - gaze-in-world
+    - custom
 SampleEmbedding:
   name: SampleEmbedding
   display_name: Sample Embedding
@@ -3348,17 +3528,55 @@ ScatterFraction:
     type: number
     minimum: 0
     maximum: 100
+ScreenAOIDefinition:
+  name: ScreenAOIDefinition
+  display_name: Definition of the eye-tracking Screen Area of Interest
+  description: |
+    A description of the shape of the Screen AOIs and what coordinates are used.
+    `["square", ["x_start", "x_stop", "y_start", "y_stop"]]`
+    Other options:
+    `"custom"/"circle"/"triangle", [["x", "y"], ["x", "y"], ["x", "y"], and so on.]`
+  type: object
+  items:
+    type: object
 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`.
+    Distance can either be expressed as a single numeric value indicating the shortest distance between
+    the participant's eye and the screen, or a three-coordinates array indicating the X, Y, Z distances
+    between the participant's eye and the center of the screen.
   anyOf:
     - type: number
       unit: m
+    - type: array
+      items:
+        type: number
+      minItems: 3
+      maxItems: 3
     - type: string
       enum:
         - n/a
+ScreenOrigin:
+  name: ScreenOrigin
+  display_name: Screen Coordinate System's Origin
+  description: |
+    Location of the spatial coordinates' origin for the visual stimuli presentation,
+    described by a list of two keywords such as ("top", "left") if the coordinates
+    refer to the top-left corner of the screen, or ("center", "center") if the position
+    (0, 0) is at the center or the screen's extent.
+  type: array
+  items:
+    type: string
+    maxItems: 2
+    minItems: 2
+    enum:
+      - "top"
+      - "bottom"
+      - "left"
+      - "right"
+      - "center"
 ScreenRefreshRate:
   name: ScreenRefreshRate
   display_name: Screen Refresh Rate
@@ -3373,6 +3591,8 @@ ScreenResolution:
     Screen resolution in pixel
     (for example `[1920, 1200]` for a screen of 1920-width by 1080-height pixels),
     if no screen use `n/a`.
+    `ScreenResolution` is REQUIRED when the experiment included simultaneous eye-tracking
+    recordings with `SampleCoordinateSystem` matching `"gaze-on-screen"`.
   anyOf:
     - type: array
       items:
@@ -3389,6 +3609,8 @@ ScreenSize:
     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`.
+    `ScreenSize` is REQUIRED when the experiment included simultaneous eye-tracking
+    recordings with `SampleCoordinateSystem` matching `"gaze-on-screen"`.
   anyOf:
     - type: array
       items:
@@ -3753,6 +3975,7 @@ StimulusPresentation:
   recommended:
     - OperatingSystem
     - ScreenDistance
+    - ScreenOrigin
     - ScreenRefreshRate
     - ScreenResolution
     - ScreenSize
@@ -3766,6 +3989,8 @@ StimulusPresentation:
       $ref: objects.metadata.OperatingSystem
     ScreenDistance:
       $ref: objects.metadata.ScreenDistance
+    ScreenOrigin:
+      $ref: objects.metadata.ScreenOrigin
     ScreenRefreshRate:
       $ref: objects.metadata.ScreenRefreshRate
     ScreenResolution:
@@ -3780,6 +4005,12 @@ StimulusPresentation:
       $ref: objects.metadata.SoftwareVersion
     Code:
       $ref: objects.metadata.Code
+StopTime_eyetrack:
+  name: StopTime
+  display_name: Eye-tracking recording stop time
+  description: |
+    Eye-tracking timestamp corresponding to the offset (stop) of the run.
+  type: number
 SubjectArtefactDescription:
   name: SubjectArtefactDescription
   display_name: Subject Artifact Description
diff --git a/src/schema/objects/suffixes.yaml b/src/schema/objects/suffixes.yaml
index 1e2825ced2..7a5b6e1856 100644
--- a/src/schema/objects/suffixes.yaml
+++ b/src/schema/objects/suffixes.yaml
@@ -810,6 +810,12 @@ physio:
   display_name: Physiological recording
   description: |
     Physiological recordings such as cardiac and respiratory signals.
+physioevents:
+  value: physioevents
+  display_name: Physiological events and asynchronous data
+  description: |
+    Event timing information corresponding to physiological recordings and other
+    asynchronous data such as messages.
 probseg:
   value: probseg
   display_name: Probabilistic Segmentation
diff --git a/src/schema/rules/checks/eyetrack.yaml b/src/schema/rules/checks/eyetrack.yaml
new file mode 100644
index 0000000000..3f9b24ff39
--- /dev/null
+++ b/src/schema/rules/checks/eyetrack.yaml
@@ -0,0 +1,33 @@
+EyetrackingStimulusPresentation:
+  issue:
+    code: INCOMPLETE_STIMULUS_PRESENTATION
+    level: error
+    message: |
+      `StimulusPresentation` metadata for the events file associated with {path}
+      ({associations.events.path}) must have `ScreenDistance`, `ScreenOrigin`,
+      `ScreenResolution` and `ScreenSize` fields.
+  selectors:
+    - suffix == 'physio'
+    - extension == '.tsv.gz'
+    - sidecar.PhysioType == 'eyetrack'
+    - sidecar.SampleCoordinateSystem == 'gaze-on-screen'
+  checks:
+    - associations.events.sidecar.StimulusPresentation.ScreenDistance != 'n/a'
+    - '"ScreenOrigin" in associations.events.sidecar.StimulusPresentation'
+    - associations.events.sidecar.StimulusPresentation.ScreenResolution != 'n/a'
+    - associations.events.sidecar.StimulusPresentation.ScreenSize != 'n/a'
+
+OnsetSourceConsistency:
+  issue:
+    code: MISSING_ONSET_COLUMN
+    level: error
+    message: >
+      The `physioevents.tsv.gz` file declared a `OnsetSource` of
+      {sidecar.OnsetSource}, but no such column was found in
+      {associations.physio.path}.
+  selectors:
+    - suffix == 'physioevents'
+    - extension == '.tsv.gz'
+    - sidecar.OnsetSource
+  checks:
+    - intersects([sidecar.OnsetSource], associations.physio.sidecar.Columns)
diff --git a/src/schema/rules/files/raw/task.yaml b/src/schema/rules/files/raw/task.yaml
index 8a207a7384..7a569e96d0 100644
--- a/src/schema/rules/files/raw/task.yaml
+++ b/src/schema/rules/files/raw/task.yaml
@@ -2,6 +2,7 @@
 timeseries:
   suffixes:
     - physio
+    - physioevents
     - stim
   extensions:
     - .tsv.gz
@@ -22,6 +23,7 @@ timeseries:
 timeseries__mri_no_task:
   suffixes:
     - physio
+    - physioevents
     - stim
   extensions:
     - .tsv.gz
diff --git a/src/schema/rules/sidecars/continuous.yaml b/src/schema/rules/sidecars/continuous.yaml
index 3023427138..0dd64e6277 100644
--- a/src/schema/rules/sidecars/continuous.yaml
+++ b/src/schema/rules/sidecars/continuous.yaml
@@ -19,7 +19,51 @@ PhysioHardware:
   selectors:
     - suffix == "physio"
   fields:
+    DeviceSerialNumber: recommended
     Manufacturer: recommended
     ManufacturersModelName: recommended
     SoftwareVersions: recommended
-    DeviceSerialNumber: recommended
+
+PhysioTypeRecommended:
+  selectors:
+    - suffix == "physio"
+  fields:
+    PhysioType: recommended
+
+PhysioTypeRequired:
+  selectors:
+    # Avoid automated validation; this is for the sake of rendering a table.
+    - "false"
+  fields:
+    PhysioType: required
+
+PhysioEvents:
+  selectors:
+    - suffix == "physioevents"
+  fields:
+    Columns: required
+    Description: recommended
+    OnsetSource: required
+
+# Eye-tracking
+EyeTrack:
+  selectors:
+    - suffix == "physio"
+    - sidecar.PhysioType == "eyetrack"
+  fields:
+    RecordedEye: required
+    SampleCoordinateSystem: required
+    AverageCalibrationError: recommended
+    CalibrationCount: recommended
+    CalibrationPosition: recommended
+    CalibrationType: recommended
+    CalibrationUnit: recommended
+    EyeCameraSettings: recommended
+    EyeTrackerDistance: recommended
+    EyeTrackingMethod: recommended
+    FeatureDetectionSettings: recommended
+    GazeMappingSettings: recommended
+    MaximalCalibrationError: recommended
+    PupilFitMethod: recommended
+    RawDataFilters: recommended
+    ScreenAOIDefinition: recommended
diff --git a/src/schema/rules/tabular_data/physio.yaml b/src/schema/rules/tabular_data/physio.yaml
index 272c4b7cc0..04f77c88ab 100644
--- a/src/schema/rules/tabular_data/physio.yaml
+++ b/src/schema/rules/tabular_data/physio.yaml
@@ -7,3 +7,29 @@ PhysioColumns:
     respiratory: optional
     trigger: optional
   additional_columns: allowed
+
+PhysioEyeTracking:
+  selectors:
+    - sidecar.PhysioType == "eyetrack"
+  columns:
+    timestamp__eyetrack: required
+    x_coordinate: required
+    y_coordinate: required
+    pupil_size: optional
+  initial_columns:
+    - timestamp__eyetrack
+    - x_coordinate
+    - y_coordinate
+  additional_columns: allowed
+
+PhysioEventsColumns:
+  selectors:
+    - suffix == "physioevents"
+  columns:
+    onset__physioevents: required
+    duration: recommended
+    trial_type: optional
+    message: optional
+  initial_columns:
+    - onset__physioevents
+  additional_columns: allowed
diff --git a/tools/schemacode/src/bidsschematools/tests/test_expressions.py b/tools/schemacode/src/bidsschematools/tests/test_expressions.py
index 2616b7c2fc..ffd5061164 100644
--- a/tools/schemacode/src/bidsschematools/tests/test_expressions.py
+++ b/tools/schemacode/src/bidsschematools/tests/test_expressions.py
@@ -66,7 +66,9 @@ def test_selectors(schema_obj):
         for key in keys:
             for selector in rules[key]:
                 ast = expression.parse_string(selector)[0]
-                assert isinstance(ast, ASTNode)
+                # A literal `false` or `0` value may be used to ensure an expression
+                # always fails. These show up as strings and ints.
+                assert isinstance(ast, (ASTNode, str, int))
 
 
 def test_checks(schema_obj):