anchor.diff:    (containing-location-class 
      (mapcar (lambda (d) (eval d).location-class) monomers)))
   
  -;;;; (defun unreference-graph-vertex-label (x)
  -;;;;   "Removes the field label from a graph label - 
  -;;;;    e.g., KSR.A -> KSR and (0 KSR.A) -> (0 KSR)"
  -;;;;   (cond
  -;;;;    ((fld-form-p x) (fld-form-object x))
  -;;;;    ((consp x)      (list* (first x) (fld-form-object (second x))
  -;;;;                           (cddr x)))
  -;;;;    (t              (error "Unexpected label ~S - expecting a FLD-FORM" x))))
  -
  -;;;; (defun unreference-graph-labels (g)
  -;;;;   (map-into (gtools:graph-labels g)
  -;;;;             #'unreference-graph-vertex-label)
  -;;;;   g)
   ;;;
   ;;; BUILD-COMPLEX-GRAPH: internal work-horse which builds the actual GRAPH structure, 
   ;;;                      from data produced by the parser
  
positive.code:                      with either other site offsets or values
           PATTERNP is always NIL."
    (let ((pattern-detected-p nil)
          (default-rest-args     '(%%default))
          (sites              (map 'list #'identity (monomer-sites monomer-object))))
      (labels
          ((site-error (binding si msg &rest args)
  
negative.code:    (etypecase x
       (list (make-complex-graph x force-pattern))
       (complex-graph x))))
  
  
  ;;;
  ;;; COMPLEX GRAPH - graph structure
  