docs: function parse_XTI(blob, length, opts) {
  	var w = opts.biff > 8 ? 4 : 2;
  	var iSupBook = blob.read_shift(w), itabFirst = blob.read_shift(w,'i'), itabLast = blob.read_shift(w,'i');
  	return [iSupBook, itabFirst, itabLast];
  }