diff --git a/Forum-Sharing-Client.md b/Forum-Sharing-Client.md
index e7a1c3e..fe333af 100644
--- a/Forum-Sharing-Client.md
+++ b/Forum-Sharing-Client.md
@@ -8,7 +8,7 @@ The client uses a separate BSP group for each pair of contacts. The [group descr
 
 ### Message types
 
-The sharing protocol uses five message types. The messages referring to each forum constitute a session.
+The sharing protocol uses five message types. All communication happens between two contacts, who have symmetrical roles. The messages referring to each forum constitute a session.
 
 **0: INVITE** - Sent by the inviter to the invitee. The message body is a BDF list with four elements: `messageType` (int), `previousMessageId` (unique ID or null), `descriptor` (list), and `message` (string or null).