anchor.diff:      : IDENT 
       | ALPHA 
       | EXPRESSION 
  +    | CHARSET
       ;
   
   // ==============================================================
  
positive.code: // Some special identifiers
  EXPRESSION : E X P R E S S I O N        ;
  ALPHA      : A L P H A                  ;
  
  // -------------
  // Identifier.  Identifier tokens pick up properties names and values
  
negative.code: IMPORT_SYM      : '@' I M P O R T       ;
  PAGE_SYM        : '@' P A G E           ;
  MEDIA_SYM       : '@' M E D I A         ;
  
  
  IMPORTANT_SYM   : '!' (WS|COMMENT)* I M P O R T A N T   ;
  