What variables should I check in IPN POST requests after a successful payment has been confirmed?
I have developed the IPN listener side of a PayPal-enabled website which records user subscriptions. Currently when I am interested for a successful transaction I look for the `payment_status` variable, ensuring that `payment_status == "Completed"`, but as can be clearly noted in the PayPal IPN variables reference, there's lots of them and I can't say whether I'm overlooking some.
So, in the end, my questions are:
Is a payment transaction considered successful if and only if `payment_status == "Completed"`, or is there any other variable that can determine it?
Are there any other important or common states associated with a payment transaction that is worth considering?