A JavaOriel driver may constrain a frame to only contain these members. More about this later in this document. The frame's location has nothing to do with its contents, it is only for user convience. Each frame is considered an instance of a prototype. There are no classes in Casbah, only prototypes.
Prototypes define a set of defaults for an object instance.
When a slot is not defined in a frame, the prototype is searched for the slot. Prototypes themselves are nothing more than a normal frame. Prototypes don't contain any special slots, they are prototypes merely by the fact that another frame points to it, asking it to become its prototype. The Casbah Access Model utilizes a specially named slot in a frame in order to implement its functionality.