anchor.diff:     ;
   
   triggertransitions
  -   : triggertransition
  -   | triggertransitions triggertransition
  +   : triggertransition+
      ;
   
   triggertransition
  
positive.code:    ;
  
  def_list
     : def_elem
     | def_list COMMA def_elem
     ;
  
  def_elem
     : collabel EQUAL def_arg
     | collabel
     ;
  
  def_arg
  
negative.code:    ;
  
  window_definition_list
     : window_definition (COMMA window_definition)*
     ;
  
  window_definition
  