---- code ----
$orderstring = $date."\t".	//current time
	$tireqty." tires\t".	//received form field
	$oilqty." oil\t".	//received form field
	$sparkqty." sparks\t".	//received form field
	$totalamount."\t".	/calc. from form fields
	$address."\n";		//received form field

$fp = fopen("orders.txt", "a");
fwrite($fp, $orderstring);
fclose($fp);

---- output in orders.txt ----
22:32 19th Saturday 2002	4 tires	1 oil	12 sparks	503.80	NL
22:32 19th Saturday 2002	 tires	 oil	 sparks	0.00	

Bug:
When using fopen() in mode a or a+ the last line will be added without
any obvious cause.
When fopen() is used in same code but in mode w it works correct like
expected.
I haven't tested fopen() in all other available modes.