3.3.5.2.6.2 Sending Move/Size Start PDU
This PDU is sent by the server when a user attempts to move or resize a local RAIL window (for example, by dragging the window title with the mouse or resizing the window borders with the mouse), and the corresponding keyboard input or mouse input forwarded to the server causes the corresponding remote window to begin the move or resize. It is initialized as specified in section 2.2.2.7.2.
This PDU SHOULD be sent if the client and server both support local move/size features. It SHOULD be sent immediately after the Min Max Info PDU (see section 2.2.2.7.1).