// Funktionen für die xls-Datei Erstellng:
function xlsBOF() {
    echo pack("ssssss", 0x809, 0x8, 0x0, 0x10, 0x0, 0x0);  
    return;
}

function xlsEOF() {
    echo pack("ss", 0x0A, 0x00);
    return;
}

function xlsWriteNumber($Row, $Col, $Value) {
    echo pack("sssss", 0x203, 14, $Row, $Col, 0x0);
    echo pack("d", $Value);
    return;
}

function xlsWriteLabel($Row, $Col, $Value ) {
    $L = strlen($Value);
    echo pack("ssssss", 0x204, 8 + $L, $Row, $Col, 0x0, $L);
    echo $Value;
return;
}

// Datei zusammenbauen
  // Header erstellen
    header("Pragma: public");
    header("Expires: 0");
    header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
    header("Content-Type: application/force-download");
    header("Content-Type: application/octet-stream");
    header("Content-Type: application/download");;
    header("Content-Disposition: attachment;filename=Dateiname.xls ");
    header("Content-Transfer-Encoding: binary ");

  // Inhalt erstellen
    xlsBOF();
    xlsWriteLabel(3,1,"Wert");
    xlsWriteNumber(3,2,"123");
    xlsEOF();