diff --git a/lib/resources/r4/communication.yaml b/lib/resources/r4/communication.yaml
index 29d4df7f7..0b2327fa6 100644
--- a/lib/resources/r4/communication.yaml
+++ b/lib/resources/r4/communication.yaml
@@ -34,6 +34,10 @@ fields:
   type: CodeableConcept
   description: Codeable definition of the communication type.
   url: https://hl7.org/fhir/r4/communication-definitions.html#Communication.category
+  note: |
+    <ul>
+      <li>Only CommunicationCategory values of <code>notification</code> and <code>reminder</code> and SNOMED CT <code>312853008</code> are supported.</li>
+    </ul>
   example: |
     {
       "category": [