public override void WriteComment( string text ) {
Debug.Assert( text != null );
bufBytes[bufPos++] = (byte) '<';
bufBytes[bufPos++] = (byte) '!';
bufBytes[bufPos++] = (byte) '-';
bufBytes[bufPos++] = (byte) '-';
WriteCommentOrPi( text, '-' );
bufBytes[bufPos++] = (byte) '-';
bufBytes[bufPos++] = (byte) '-';
bufBytes[bufPos++] = (byte) '>';
}