diff --git a/Transport-Properties-Client.md b/Transport-Properties-Client.md
index 0282420..6e118b1 100644
--- a/Transport-Properties-Client.md
+++ b/Transport-Properties-Client.md
@@ -1,16 +1,18 @@
 The transport properties client is a [BSP client](BSP) that synchronises transport properties between pairs of devices. Transport properties describe how to connect to a device over various transports.
 
-### Group identifiers
+### Identifier
 
-The client's identifier is `org.briarproject.bramble.transport`.
+The client's identifier is `org.briarproject.bramble.transport`. The major version is 0.
 
-The client uses a separate 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.
 
 The client also uses a group with an empty descriptor for storing local transport properties. This group is not shared with any contacts.
 
 ### Message types
 
-**UPDATE** - The message body is a BDF list with three elements: `transportId` (string), `version` (int), and `properties` (dictionary). `transportId` and `properties` are supplied by the transport plugin. `version` is incremented whenever the properties change.
+**UPDATE** - The message body is a BDF list with three elements: `transportId` (string), `version` (int), and `properties` (dictionary). `transportId` and `properties` are supplied by the transport plugin. The keys and values of `properties` are strings. `version` is incremented whenever the properties change.
 
 ### Validity policy