anchor.diff:     | name
      | string
      | ('(' expression ')')
  -   | ((number | name)? '[' expression ']')
  -   | NOT expression
  -   ;
  +   | ('[' expression ']')
  +   | gross
  +   ;
  +
  +/*
  + MASM allows instruction names such as "RET" to be label names.
  +*/
  +gross
  +    : INSTRUCTION
  +    ;
   
   dollar
      : DOLLAR
  
positive.code:    ;
  
  STRING2
     : '\'' ~ ['\'']* '\''
     ;
  
  
  
negative.code:    : P T R
     ;
  
  REGISTER
     : A X | B X | C X | D X | C I | D I | B P | S P | I P | C S | D S | E S | S S
     ;
  