anchor.diff:     "Return an approximation of the current line number, or NIL.")
     (:method ((handler sax-parser-mixin))
       (if (sax-parser handler)
  -	(line-number (sax-parser handler))
  -	nil)))
  +        (line-number (sax-parser handler))
  +        nil)))
   
   (defgeneric column-number (sax-parser)
     (:documentation
      "Return an approximation of the current column number, or NIL.")
     (:method ((handler sax-parser-mixin))
       (if (sax-parser handler)
  -	(column-number (sax-parser handler))
  -	nil)))
  +        (column-number (sax-parser handler))
  +        nil)))
   
   (defgeneric system-id (sax-parser)
     (:documentation
  
positive.code: (defclass content-handler (abstract-handler) ())
  (defclass default-handler (content-handler) ())
  
  
  ;;;; EVENTS
  
  (macrolet ((define-event ((name default-handler-class)
  			  (&rest args)
  			  &body hax-body)
  	     `(defgeneric ,name (handler ,@args)
  		(:method ((handler null) ,@args)
  		  (declare (ignore ,@args))
  		  nil)
  		(:method ((handler t) ,@args)
  		  (declare (ignore ,@args))
  		  (warn "deprecated SAX default method used by a handler ~
                           that is not a subclass of SAX:ABSTRACT-HANDLER ~
                           or HAX:ABSTRACT-HANDLER")
  		  nil)
  		(:method ((handler abstract-handler) ,@args)
  		  (declare (ignore ,@args))
  		  (error "SAX event ~A not implemented by this handler"
  			 ',name))
  		(:method ((handler ,default-handler-class) ,@args)
  		  (declare (ignore ,@args))
  		  nil)
  		(:method ((handler hax:abstract-handler) ,@args)
  		  (declare (ignorable ,@args))
  		  ,@hax-body))))
    (define-event (start-document default-handler)
        ()
      nil)
  
    (define-event (start-element default-handler)
        (namespace-uri local-name qname attributes)
      (setf attributes
  	  (remove "http://www.w3.org/2000/xmlns/"
  		  attributes
  		  :key #'attribute-namespace-uri
  		  :test #'equal))
      (hax:start-element handler local-name attributes))
  
    (define-event (start-prefix-mapping content-handler)
        (prefix uri)
      nil)
  
    (define-event (characters default-handler)
        (data)
      (hax:characters handler data))
  
    (define-event (unescaped default-handler)
        (data)
      (hax:unescaped handler data))
  
    (define-event (processing-instruction default-handler)
        (target data)
      nil)
  
    (define-event (end-prefix-mapping content-handler)
        (prefix)
      nil)
  
    (define-event (end-element default-handler)
        (namespace-uri local-name qname)
      (hax:end-element handler local-name))
  
    (define-event (end-document default-handler)
        ()
      (hax:end-document handler))
  
    (define-event (comment content-handler)
        (data)
      (hax:comment handler data))
  
    (define-event (start-cdata content-handler)
        ()
      nil)
  
    (define-event (end-cdata content-handler)
        ()
      nil)
  
    (define-event (start-dtd content-handler)
        (name public-id system-id)
      (hax:start-document handler name public-id system-id))
  
    (define-event (end-dtd content-handler)
        ()
      nil)
  
    (define-event (start-internal-subset content-handler)
        ()
      nil)
  
    (define-event (end-internal-subset content-handler)
        ()
      nil)
  
    (define-event (unparsed-internal-subset content-handler)
        (str)
      nil)
  
    (define-event (unparsed-entity-declaration content-handler)
        (name public-id system-id notation-name)
      nil)
  
    (define-event (external-entity-declaration content-handler)
        (kind name public-id system-id)
      nil)
  
    (define-event (internal-entity-declaration content-handler)
        (kind name value)
      nil)
  
    (define-event (notation-declaration content-handler)
        (name public-id system-id)
      nil)
  
    (define-event (element-declaration content-handler)
        (name model)
      nil)
  
    (define-event (attribute-declaration content-handler)
        (element-name attribute-name type default)
      nil)
  
    (define-event (entity-resolver content-handler)
        (resolver)
      nil)
  
    (define-event (dtd content-handler)
        (dtd)
      nil))
  
  ;;; special case: this method is defined on abstract-handler through
  ;;; sax-parser-mixin
  
negative.code:     general external entity are being processed.")
    (:method ((handler sax-parser-mixin))
      (if (sax-parser handler)
          (system-id (sax-parser handler))
          nil)))
  
  (defgeneric xml-base (sax-parser)
    (:documentation
  