Stephen,

> Implementation note: Attaching unique documentation to each instance
> would be possible if Squeak had finalizers and weak pointers.  An
> instance being expunged by the garbage collector could, in its
> finalizer, remove itself and its documentation from a global
> Explanation dictionary.

I imagined it a little bit different: the explanation is, in some
sense, inside the instance (e.g., Object may have instance variable
'explanation').

> On a slight tangent: It seems to me that a documentation browser would
> be even more important in a prototype-based system, since there would
> be no class hierarchy to help a user find information.

The key is right here.  In a prototype-based system we explicitly
regard everything as objects, and want documentation for all objects.
But in Smalltalk, what forces us to only put comments on objects
which are kinds of Class?

Boris