All cart operations except CartClear return a value for PurchaseURL, for example:

<PurchaseURL>https://www.amazon.com/gp/cart/aws-merge.html?cart-id=002-9918938-1696046%26associate-id=[Your ID]%26hmac=b0ogzvivVYLXjSZ9WwoBRFesFYU=%26AWSAccessKeyId=[Access Key ID%26MergeCart=False<PurchaseURL>

This value is a URL that should be submitted, like a request, to purchase the items in a remote shopping cart. The value contains the Associate's Tag if it was specified in the CartCreate operation. The Associate's Tag value in the PurchaseURL is what links the customer's purchase to the Associate. If the PurchaseURL is not used to buy the items in a cart, the Associate will not receive credit for the sale.

The information in bold includes:

You can manually change any of the values in the PurchaseURL but that is not recommended.

The following is an HTML implementation of the PurchaseURL.

<form name=”Proceed to Checkout” method=”post”
action=https://www.amazon.com/gp/cart/aws-merge.html?cart-id=002-9918938-1696046%26associate-id=[Your ID]%26hmac=b0ogzvivVYLXjSZ9WwoBRFesFYU=%26AWSAccessKeyId=[Access Key ID%26MergeCart=False>
  <input type="submit" name="Proceed to Purchase" 
  value="
          PurchaseURL
         Purchase" >
</form>