This is a subclass of HTML::Mason::Component.
Mason uses it to implement both subcomponents (defined by <%def>) and methods (defined by <%method>).
A subcomponent/method gets most of its properties from its owner.
Note that the link from the subcomponent to its owner is a weak reference (to prevent circular references),
so if you grab a subcomponent/method object,
you should also grab and hold a reference to its owner.
If the owner goes out of scope,
the subcomponent/method object will become unusable.