anchor.diff:          TOKINTERFACE
           ( typevar_item VAR SEMICOLON
           | VAR
  -            ( EQUAL assign_value SEMICOLON
  +            ( equal_value SEMICOLON
               | VAR
  -                ( EQUAL assign_value SEMICOLON
  +                ( equal_value SEMICOLON
                   | SEMICOLON
                       [
                           ( method_declaration )+
  
positive.code:         | TOKINTEGER | TOKBOOL | TOKSTRING | TOKREAL | TOKNAT | TOKACTION | TOKACTIONVALUE
  
      rule Type_nitem:
          #term_single
          Type_item
          | VAR [ LBRACKET NUM (COLON NUM)* RBRACKET ]
          | CLASSVAR typevar_item_or_var
  
      rule function_parameter:
          TOKFUNCTION function_argument
  
      rule formal_item:
          ( function_parameter
  
negative.code:         TOKSEQ
          statement_list
          TOKENDSEQ
  
      rule action_statement:
          TOKACTIONSTATEMENT [ COLON  VAR] [ SEMICOLON ]
  