1.134.1 Send methods

relation ->backwards: from=object, to=object

Called after to has changed. Its task is to update from accordingly.

relation ->create: from=object, to=object

Invokes relation->forwards to itself. This method is activated when the constraint object this relation is referred from is initialised.

relation ->forwards: from=object, to=object

Called after from has changed. Its task is to update to accordingly. If relation->create has not been redefined, this method is also called when the constraint object is established.