diff --git a/Forum-Sharing-Client.md b/Forum-Sharing-Client.md
index 5d8cab2..64c1c91 100644
--- a/Forum-Sharing-Client.md
+++ b/Forum-Sharing-Client.md
@@ -1,14 +1,24 @@
-The forum sharing client is a [BSP client](BSP) that allows users to share forums with their contacts, who may accept or decline the invitations.
+The forum sharing client is a [BSP client](BSP) that allows users to share forums with their contacts, who may accept or decline the invitations. It is used in conjunction with the [forum client](forum client).
 
-### Group identifiers
+### Identifier
 
-The client's identifier is `org.briarproject.briar.forum.sharing`.
+The client's identifier is `org.briarproject.briar.forum.sharing`. The major version is 0.
 
-The client uses a separate BSP group for each pair of contacts. The [group descriptor](BSP#group-identifiers) is a [BDF list](BDF) containing the unique IDs of the contacts' identities, sorted in ascending order as byte strings.
+### Groups
+
+The client uses a separate BSP group for communicating with each contact. The [group descriptor](BSP#group-identifiers) is a [BDF list](BDF) containing the unique IDs of the contacts' identities, sorted in ascending order as byte strings.
+
+### Roles
+
+All communication happens between two contacts, who have symmetrical roles.
+
+### Sessions
+
+The messages exchanged between two contacts referring to a given forum constitute a session. The forum's unique ID is used as the session ID.
 
 ### Message types
 
-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.
+The protocol uses five message types.  
 
 **0: INVITE** - Sent by either party to start or restart a session. The message body is a BDF list with four elements: `messageType` (int), `previousMessageId` (unique ID or null), `descriptor` (list), and `message` (string or null).