anchor.diff:  
   (defmethod slot-unbound (class (dist dist) (slot (eql 'provided-systems)))
     (declare (ignore class))
  -  (initialize-indexes dist)
  +  (initialize-system-index dist)
     (setf (slot-value dist 'provided-systems)
           (loop for system being each hash-value of (system-index dist)
                 collect system)))
   
   (defmethod slot-unbound (class (dist dist) (slot (eql 'provided-releases)))
     (declare (ignore class))
  -  (initialize-indexes dist)
  +  (initialize-release-index dist)
     (setf (slot-value dist 'provided-releases)
           (loop for system being each hash-value of (release-index dist)
                 collect system)))
  
positive.code: (defmethod provided-systems ((system system))
    (list system))
  
  (defmethod initialize-indexes ((dist dist))
    (let ((systems (ensure-system-index-file dist))
          (index (make-hash-table :test 'equal)))
      (call-for-each-index-entry
       systems
       (lambda (line)
  
negative.code:    if necessary."))
  
  
  (defgeneric initialize-release-index (dist)
    (:documentation
     "Initialize the release index of DIST."))
  
  (defgeneric initialize-system-index (dist)
    (:documentation
     "Initialize the system index of DIST."))
  
  
  (defgeneric local-archive-file (release)
  