paypal form shipping variables in php

I used to use the paypal form variable to post shipping value to paypal like this,

<input type="hidden" name="shipping_1" value="<?php echo number_format($cost_shipping,2); ?>">

But paypal does not receive shipping value from that variable anymore, instead,

<input type="hidden" name="handling_cart" value="<?php echo开发者_运维技巧 number_format($cost_shipping,2); ?>">

And I receive this list of datas in the page return path from paypal,

... 
'mc_shipping' => string '0.00' (length=4)
'mc_handling' => string '0.60' (length=4)
...

What is the different between mc_shipping and mc_handling?

I tested the cart by buying 2 items, so I think paypal then return them in numbers like this,

'mc_handling1' => string '0.00' (length=4)
'mc_handling2' => string '0.00' (length=4)
'mc_shipping1' => string '0.00' (length=4)
'mc_shipping2' => string '0.00' (length=4)

How can I pass value to paypal if each product/ item has different shipping cost and I want list them separately?

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There are different charges for shipping and handling.

Here is a nice article to help you understand the difference between shipping and handling.

http://www.wisegeek.com/what-are-shipping-and-handling-fees.htm