An ObjectMessage is sent to AnObject and consists of the ReceiverObject (someObject in the following example), the InstanceMethod that is being called (doSomethingWithObject:andAnotherObject: in the example), and any arguments that are passed to it (theFirstObject and theSecondObject in the example).
[someObject doSomethingWithObject: theFirstObject andAnotherObject: theSecondObject];
usually just called “Message”, but we can’t make a link out of that and MessAge is just too, uh, mess-y
And, in fact, you can send an ObjectMessage to a ClassObject, since a class is an object in our neck of the woods.
see also MethodSignature
see also SeLector