Here you need to enter which shipping methods could possibly be combined with certain
payment methods or vice versa. If an item is checked this means that this particular
combination is permitted. All combinations are activated by default after setting a
new shipping or payment method.
In this example:
If a shopper chooses Worldpay or Protx as a payment method, then he can choose Royal Mail or DHL as the Shipping method.
If a shopper chooses PayPal, the the only shipping method available
for is Royal Mail