The ALERT-C protocol is designed to provide mostly event-orientated road end-user information messages. Many "hooks" have been left for future development and indeed a few status-orientated road end-user information messages were included. This protocol is designed to be closely linked to the ALERT-Plus protocol, which is specifically designed for status-orientated road end-user information; both protocols may be available in the same RDS transmission. The ALERT-Plus protocol is specified in ENV 12313-4.