The class Player may have many subclasses, each one associated with a Morph object with the help of a MorphExtension object.
The basic definition is that a Morph object may have, i.e. optionally, a Player associated with it. From the point of view of the player object the
the associated Morph is the "costume" if "wears". The Player object itself is a class with lots of capability but very little instance state; user-defined Players are all implemented as compact, single-instance subclasses of Player
The fundamental user-scriptable entity. Always represented by a user-specific subclass of Player;
instance vars and methods relate to user-defined structures.
costume is a Morph, the primary morph I am currently wearing for graphical display.
Scripts are defined in subclasses of Player. These are UniClasses.
Messages in scripts are sent to Players. A Player may delegate to its costume, or to an object the costume suggests. Or, a Player may designate some other object to receive the script messages it does not understand. (see doesNotUnderstand:)