anchor.diff:     | ptr expression
      | NOT expression
      | OFFSET expression
  +   | LENGTH expression
      ;
   
   ptr
  
positive.code:    | title
     | include
     | rw
     ;
  
  rw
     : name? RW expression
     ;
  
  cseg
  
negative.code:    ;
  
  
  RB
     : R B
     ;
  
  
  RS
     : R S
     ;
  
  
  LENGTH
     : L E N G T H
     ;
  
  
  COMMENT
     : ';' ~ [\r\n]*
     ;
  