Draft sample entity

src/02-common-principles.md

@@ -32,6 +32,13 @@ misunderstanding we clarify them here.
     context, a session may also indicate a group of related scans,
     taken in one or more visits.
 
+1.  **Sample** - a sample pertaining to a subject such as tissue, primary cell
+    or cell-free sample.
+    The `sample-<label>` key/value is used to distinguish between different
+    samples from a same subject.
+    The label MUST be unique per subject and is RECOMMENDED to be unique
+    throughout the dataset.
+
 1.  **Data acquisition** - a continuous uninterrupted block of time during which
     a brain scanning instrument was acquiring data according to particular
     scanning sequence/protocol.

src/schema/entities.yaml

@@ -25,6 +25,17 @@ session:
     often in the case of some intervention between sessions
     (for example, training).
   format: label
+sample:
+  name: Sample
+  entity: sample
+  description: |
+    A sample pertaining to a subject such as tissue, primary cell
+    or cell-free sample.
+    The `sample-<label>` key/value is used to distinguish between different
+    samples from a same subject.
+    The label MUST be unique per subject and is RECOMMENDED to be unique
+    throughout the dataset.
+  format: label
 task:
   name: Task
   entity: task