anchor.diff:  IMPORT_SYM      : '@' I M P O R T       ;
   PAGE_SYM        : '@' P A G E           ;
   MEDIA_SYM       : '@' M E D I A         ;
  -CHARSET_SYM     : '@charset'            ;
   
   
   IMPORTANT_SYM   : '!' (WS|COMMENT)* I M P O R T A N T   ;
  
positive.code: styleSheet  
      : WS*
        (charSet WS!*)?
        (cssImport WS!*)*
        (bodyset WS!*)*
        EOF!
      ;
  
negative.code: // Character set.   Picks up the user specified character set, should it be present.
  //
  charSet
      : '@' CHARSET WS+ STRING WS* SEMI
      -> ^(CHARSET STRING)
      ;
  
  // ---------
  // Import.  Location of an external style sheet to include in the ruleset.
  //
  importFile
      : IMPORT_SYM WS+ importLocation  (WS+ medium (WS* COMMA WS* medium)*)? WS* SEMI
      -> ^(IMPORT importLocation medium*)
      ;
      
  importLocation : STRING|URI ;
  
  // ---------
  // Media.   Introduce a set of rules that are to be used if the consumer indicates
  