INSTANCE-OF
===========

syntax: (instance-of <frame-name>
           {<relation-name>
           ([:VALUE <lisp-type: T>]
           [:READ-DEPENDENT <lisp-type: T>]
           [:WRITE-DEPENDENT <lisp-type: T>])}*)

Problem: local let-variables as arguments to
         :value must be pre-evaluated, before
         they loose validity!

This function makes a dynamic instance.
Dynamic instances are not controlled by
the system. If they have to be used, 
they have to be linked to a variable.

See the page on RELATION-SPECIFICATION, too!

example: >(instance-of sportsman
             first-name (:value "Ben")
             last-name (:value "Johnson"))
         ==>#<anonymus>