diff --git a/lib/types/message-types.js b/lib/types/message-types.js
--- a/lib/types/message-types.js
+++ b/lib/types/message-types.js
@@ -97,9 +97,9 @@
 
 export const messageTypes = Object.freeze({
   TEXT: 0,
-  CREATE_THREAD: 1,
+  CREATE_THREAD: 1, // appears in the newly created thread
   ADD_MEMBERS: 2,
-  CREATE_SUB_THREAD: 3,
+  CREATE_SUB_THREAD: 3, // appears in the parent when a child thread is created (historically also when a sidebar was created)
   CHANGE_SETTINGS: 4,
   REMOVE_MEMBERS: 5,
   CHANGE_ROLE: 6,
@@ -119,7 +119,7 @@
   MULTIMEDIA: 15,
   UPDATE_RELATIONSHIP: 16,
   SIDEBAR_SOURCE: 17,
-  CREATE_SIDEBAR: 18,
+  CREATE_SIDEBAR: 18, // appears in the newly created sidebar
 });
 export type MessageType = $Values<typeof messageTypes>;
 export function assertMessageType(ourMessageType: number): MessageType {