Message is a string containing the message to be sent
Class is the type of message (used for clients and such). An example would be 'combat', 'shout', 'emergency' etc.
target is a list of objects to be sent the message. This can be either a single object string or object pointer, or may be an array of either. If a target is non living all objects in it's environment will receive the message.
Exclude is a list of objects that should not receive the message. This can either be one object or an array of objects.