3.2.5.1.1 Constructing Client MCS Connect Initial PDU
The Client MCS Connect Initial PDU is constructed by the client during the connection establishment phase, as specified in [MS-RDPBCGR] section 3.2.5.3.3.
For remote applications integrated locally (RAIL) clients, the clientNetworkData field (as specified in [MS-RDPBCGR] section 2.2.1.3) MUST be present and MUST contain a CHANNEL_DEF structure in channelDefArray for the RAIL virtual channel. This informs the server that the client wants to use a static virtual channel for communicating RAIL virtual channel messages.<26>