anchor.diff:          {
               String signature = author;
               
  -            if( link != null )
  +            if( link != null && link.length() > 0 )
               {
                   link = HttpUtil.guessValidURI( link );
                   
  
positive.code:     NDC.push( wiki.getApplicationName()+":"+pagereq );
      
      WikiSession wikiSession = wikiContext.getWikiSession(); 
      String user = wikiSession.getUserPrincipal().getName();
      if ( wikiSession.isAnonymous() ) 
      {
          user  = request.getParameter( "author" );
      }
      String action  = request.getParameter("action");
      String ok      = request.getParameter("ok");
      String preview = request.getParameter("preview");
      String cancel  = request.getParameter("cancel");
      String edit    = request.getParameter("edit");
      String author  = request.getParameter( "author" );
      String link    = request.getParameter( "link" );
      String remember = request.getParameter("remember");
  
      WikiPage wikipage = wikiContext.getPage();
  
negative.code:     else if( preview != null )
      {
          log.debug("Previewing "+pagereq);
          pageContext.forward( "Preview.jsp?action=comment" );
          return;
      }
      else if( cancel != null )
      {
  