Message code is assigned to a particular event type, and is encoded as a 32-bit number in the following way: The MSB 8 bits are reserved. The next 8 bits represent a particular subsystem or component. The LSB 16 bits are the keycode id within the subsystem. For example, Remote Copy Target Down event has a subsystem ID of 37 (remote copy subsystem), and a keycode ID of 1, thus the message code for this event = ((37 << 16) | 1) = 0x250001 = 2424833. This is shown as 'Message Code' in the CLI 'showalert' display, and also shows up in the Alerts Details Pane in the GUI.