anchor.diff:  TOK_WS
      : Ws+ -> type (WS) , channel (OFF_CHANNEL)
      ;
  -   // -------------------------
  -
  +
  +// -------------------------
   mode Channels;
   // currently same as Tokens mode; distinguished by keyword
   CHN_DOC_COMMENT
  
positive.code: ACTION_CONTENT
     : .
     ;
     // -------------------------
  
  mode Options;
  OPT_DOC_COMMENT
     : DocComment -> type (DOC_COMMENT) , channel (COMMENT)
  
negative.code: CHN_WS
     : Ws+ -> type (WS) , channel (OFF_CHANNEL)
     ;
  
  // -------------------------
  mode LexerCharSet;
  LEXER_CHAR_SET_BODY
     : (~ [\]\\] | EscAny)+ -> more
  