3.1.3 Initialization
The static virtual channel between the client and the server MUST be established before protocol operations can commence (see section 1.3.2.1 for an overview).
The Handshake PDU (as specified in section 2.2.2.2.1) is exchanged between the server and the client to establish that both endpoints are ready to begin RAIL mode.
The Client Information PDU (as specified in section 2.2.2.2.2) is sent from a client to a server and contains information about RAIL client state and features supported by the client.