...
The URL itself is a dynamic URL and has a parameter indicated by {so}. Remember that we have a control in the form named 'so' (defined in Modifytheform this step. When the value of the control named 'so' changes (which will happen when the user selects a particular order), frevvo will automatically issue an HTTP GET to the above URL using the new order number and will dynamically update the order details including creating new line items, removing old ones etc. without refreshing the form as shown in the picture below.
...