- from `upper' and the bottom class in this tree is
- `bottom_class'. The classes in this tree are super classes of
- `bottom_class'. `subclasses' member of each tree node point to the
- next subclass tree node. */
+ from `upper' and the bottom class in this tree is `bottom_class'.
+ If `upper' is Nil, creates a class hierarchy up to a root class.
+ The classes in this tree are super classes of `bottom_class'. The
+ `subclasses' member of each tree node point to the list of
+ subclasses for the node. */