Payment Notification API Question

I have successfully written a Payment Notification handler and specified the URL in Payment Notifications URL. It is being fired, so that part is working.

I am using Authorize.net and need to discern between an initial payment (setup of ARB) and subsequent recurring payments. Is there any information that is “passable” to the handler or that can be gleaned from the usermeta data that can help me know if this is a first time payment or a repeating payment? I have a database table that needs to be populated on initial payment but the handler can just exit on subsequent payments.

Thanks,
Keith

Is there any information that is “passable” to the handler or that can be gleaned from the usermeta data that can help me know if this is a first time payment or a repeating payment?

s2Member provides a lot of replacement codes that are possible to your handler via GET variables. For Payment Notifications you have these:

In addition, you can load in WordPress and use s2Member’s API Functions in your API Notification Handler.

See: s2Member® » Codex » API Functions