anchor.diff:  (defstruct (internal-entdef
               (:include entdef)
               (:constructor make-internal-entdef (value))
  -            (:conc-name #:ENTDEF-))
  +            (:conc-name #:entdef-))
     (value (error "missing argument") :type rod)
     (expansion nil))
   
   (defstruct (external-entdef
               (:include entdef)
               (:constructor make-external-entdef (extid ndata))
  -            (:conc-name #:ENTDEF-))
  +            (:conc-name #:entdef-))
     (extid (error "missing argument") :type extid)
     (ndata nil :type (or rod null)))
   
  
positive.code:          (car (nth-value 1 (peek-token input)))
           (cdr (nth-value 1 (peek-token input))))))
      (consume-token input)))
    
  (defun p/document
      (input handler
       &key validate dtd root entity-resolver disallow-internal-subset)
    (let ((*ctx*
           (make-context :handler handler
                         :entity-resolver entity-resolver
  
negative.code: 
  (defun absolute-uri (sysid source-stream)
    (let ((base-sysid (zstream-base-sysid source-stream)))
      ;; XXX is the IF correct?
      (if base-sysid
          (puri:merge-uris sysid base-sysid)
          sysid)))
  
  (defstruct (extid (:constructor make-extid (public system)))
    (public nil :type (or rod null))
  