docs: function parse_RString(blob, length, opts) {
  	var end = blob.l + length;
  	var cell = parse_XLSCell(blob, 6);
  	var cch = blob.read_shift(2);
  	var str = parse_XLUnicodeStringNoCch(blob, cch, opts);
  	blob.l = end;
  	cell.t = 'str';
  	cell.val = str;
  	return cell;
  }