anchor.diff:      | (term (LT | GT | EQUALS) term)
       ;
   
  -comment
  -    : SEMICOLON ~(CR)*
  -    ;
  -
   identifier
       : IDENTIFIER
       ;
  
positive.code:     ;
  
  line
      : code 
      | routinedecl 
      | linecomment
      ;
  
  linecomment
      : comment CR
      ;
  
  code
      : SPACE+ (label SPACE*)? (command+ | if_ | subproc)? SPACE* comment? CR
      ;
  
  label
  
negative.code: fragment Y:('y'|'Y');
  fragment Z:('z'|'Z');
  
  COMMENT
      : ';' ~[\r\n]* ->skip
      ;
  
  CR
      : '\n'
      ;
  