anchor.diff:     ;
   
   alter_extension_opt_list
  -   : alter_extension_opt_list alter_extension_opt_item
  -   |
  +   : alter_extension_opt_item*
      ;
   
   alter_extension_opt_item
  
positive.code:    ;
  
  create_extension_opt_list
     : create_extension_opt_list create_extension_opt_item
     |
     ;
  
  create_extension_opt_item
  
negative.code:    ;
  
  optrolelist
     : createoptroleelem*
     ;
  
  alteroptrolelist
     : alteroptroleelem*
     ;
  
  alteroptroleelem
  