anchor.diff:  
   
       CASE iv_action.
  -      WHEN 'back'.
  -        lcl_gui=>back( ).
         WHEN 'add'.
           ls_file = file_decode( iv_getdata ).
           mo_stage->add( ls_file ).
  
positive.code: 
      CLASS-METHODS back
        RETURNING VALUE(r_exit) TYPE xfeld
        RAISING lcx_exception.
  
      CLASS-METHODS call_page
        IMPORTING ii_page TYPE REF TO lif_gui_page
  
negative.code:     ro_html->add( lcl_gui=>header( ) ).
      ro_html->add( '<div id="header">' ).
      ro_html->add( '<h1>Stage</h1>' ).
      ro_html->add( '</div>' ).
      ro_html->add( '<div id="toc">' ).
      ro_html->add( render_local( ) ).
  