Sorry, what I mean by "round trip" is information sent during the checkout and is returned to the pp_confirm page. For example the checkout form for the address. I added a checkbox to that form where the buyer is asked "Is this a new address?" with a cb for "Yes".
I noticed that this isn't being saved in the [WASF_CheckoutWizard_NewFromBlank_Default] session array after returning from PP. And it's not in the WA_getSavedFormValue('CheckoutWizard_NewFromBlank_Default','new_address') either. (new_address is the name of the cb in the form).
I do find it held in the [WASF_WA_Payments] session though and I'm currently just using this. I just wondered if there was a way to include instructions or other random information like that checkbox that would be returned back with the PayPal response. I can just use a session variable if not.