diff --git a/data/topic-schema/src/main/java/net/corda/schema/Schemas.java b/data/topic-schema/src/main/java/net/corda/schema/Schemas.java
index 7e90316f8f..f005a53d7a 100644
--- a/data/topic-schema/src/main/java/net/corda/schema/Schemas.java
+++ b/data/topic-schema/src/main/java/net/corda/schema/Schemas.java
@@ -113,6 +113,7 @@ private Flow() {
         public static final String FLOW_MAPPER_SESSION_IN = "flow.mapper.session.in";
         public static final String FLOW_START = "flow.start";
         public static final String FLOW_SESSION = "flow.session";
+        public static final String EXTERNAL_MESSAGE_SAMPLE = "external.message.sample";
     }
 
     /**
diff --git a/data/topic-schema/src/main/resources/net/corda/schema/Flow.yaml b/data/topic-schema/src/main/resources/net/corda/schema/Flow.yaml
index e270dc3367..404ab09d1e 100644
--- a/data/topic-schema/src/main/resources/net/corda/schema/Flow.yaml
+++ b/data/topic-schema/src/main/resources/net/corda/schema/Flow.yaml
@@ -81,4 +81,11 @@ topics:
       - flowMapper
       - tokenSelection
     config:
+  ExternalMessage:
+    name: external.message.sample
+    consumers:
+      - flow
+    producers:
+      - flow
+    config: