[ENH] Define channel column for events and Delimiter field for column descriptions

src/modality-specific-files/task-events.md

@@ -82,10 +82,10 @@ A guide for using macros can be found at
 Example of the content of the TSV file:
 
 ```Text
-onset	duration	trial_type	response_time	stim_file	channel	artifact
+onset	duration	trial_type	response_time	stim_file	channel	annots
 1.23	0.65	start	1.435	images/red_square.jpg	n/a	n/a
 5.65	0.65	stop	1.739	images/blue_square.jpg	n/a	n/a
-12.1	2.35	n/a	n/a	n/a	F,1|F,2|Cz	sweat
+12.1	2.35	n/a	n/a	n/a	F,1|F,2|Cz	musc
 ```
 
 In the accompanying JSON sidecar, the `trial_type` column might look as follows:
@@ -104,8 +104,15 @@ In the accompanying JSON sidecar, the `trial_type` column might look as follows:
         "Description": "Channel(s) associated with the event",
         "Delimiter": "|"
     },
-    "artifact": {
-        "Description": "Description of an artifact."
+    "annots": {
+        "LongName": "Annotations",
+        "Description": "Hierarchical Event Descriptors (HED) annotations",
+        "Levels": {
+            "musc": "Muscle artifact. A very common, high frequency, sharp artifact that corresponds with agitation/nervousness in a patient."
+        },
+        "HED": {
+            "musc": "EMG-artifact"
+        }
     }
 }
 ```
@@ -116,17 +123,17 @@ Note that in the example above:
     In a real dataset, all other columns SHOULD also be described.
 
 1.  The `channel` column contains a list of values that are separated
-    by a non-default delimiter (that is, *not* with a comma `,`).
-    See the `Delimiter` field in the accompanying JSON sidecar.
+    by a delimiter (`|`), as is declared in the `Delimiter` metadata
+    field of the `events.json file.
     Thus, the channels related to the event in the third row of the example
     are called `F,1`, `F,2`, and `Cz`.
 
-1.  The example contains a column called `artifact`.
+1.  The example contains a column called `annots`.
     This column is not defined in BIDS, and constitutes additional, arbitrary
     (that is, unofficial) metadata.
     In the present case, it is used to describe artifacts in the data,
     in reference to the `channel` column.
-    Note that in practice, such a hypothetical `artifact` column should make
+    The `annots` column is making
     use of the powerful HED system for documenting events, see below.
 
 Events MAY also be documented in machine-actionable form