anchor.diff:     | equ
      | db
      | dw
  +   | cseg
  +   | dseg
      | title
      | include
      ;
   
  +cseg
  +   : CSEG
  +   ;
  +
  +dseg
  +   : DSEG
  +   ;
  +
   dw
      : DW expressionlist
      ;
  
positive.code:    ;
  
  line
     : (assemblerdirective | instruction)? comment?
     ;
  
  instruction
     : lbl? prefix? opcode expressionlist?
     ;
  
  lbl
     : label ':'
     ;
  
  prefix
  
negative.code:    ;
  
  org
     : ORG name
     ;
  
  title
  