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+TransportApp is an application layer protocol that uses [BSP] to synchronise information about how to connect to devices over various transports.
+
+### Message types
+
+TransportApp uses a single message type:
+
+**0: PROPERTIES** - The content consists of a [BDF] list. The first element of the list is a string identifying the transport. The second element is an integer that is incremented whenever the transport properties change. The third element is a dictionary containing the transport properties.
+
+The following transports have been defined:
+
+* bt: Bluetooth RFCOMM
+* lan: TCP over local area networks, including Wi-Fi
+* tor: Tor hidden services
+* file: Removable storage devices
+
+### Storage policy
+
+* The local message with the highest version number for each transport is stored and other versions are deleted
+* For each remote device, the remote message with the highest version number for each transport is stored and other versions are deleted
+
+### Sharing policy
+
+* Local messages are shared with all remote devices
+* Remote messages are not shared with other remote devices