[AlphaCommerceHub] In which cases does AlphaHPP calculate the shopping cart product contents for a merchant?

The documentation says:

AlphaHPP can calculate the shopping cart product contents for a merchant.

developer.alphacommercehub.com.au/docs/alphahpp-#product-line-information

What does «can» mean it this sentence?
Will AlphaHPP calculate the shopping cart product contents for a merchant in every case when the OrderDetails parameter is provided, or it depends on some other factors or maybe settings?

See also:

I have got a response from AlphaCommerceHub:

This is if you pass a list of products instead of a final total. It will tally up the cost of the products in the cart to come to a final total.
In the case of magento it might be easier to just pass through a final cost of the cart, as magento has already got the final cost of the cart.