哪种结果类型更适合肥皂结果

I developed a web service using php and SOAP.

I'm concerned to now which type is better for method results.

Assume I have a method named taxCalculator; this method returns an array with this structure :

    $resultArray = array(
                        "pureTax"      => $pureTax,
                        "finalValue"   => $finalValue,
                        "taxInPercent" => $tax,
                    );

    return $resultArray;

But I'm not sure that this type of array is usefull for users that transact with my service with other programming languages or platforms.

The second way could be something like this :

value1 . delimiter . value2 . delimiter . value3 . delimiter

and in this case :

$result = $pureTax . '^' . $finalValue . '^' . $tax
return $result;

Does any one have any suggestion or better way?

Thanks in Advance