问题
Example: paypal recurring payments form
When I have one enabled, it changes "for one month" to "for each month" on the checkout form, so why do I need two of them?
I've looked for the variables here and cannot find it. https://developer.paypal.com/webapps/developer/docs/classic/ipn/integration-guide/IPNandPDTVariables/#id091EB0901HT
回答1:
You can see descriptions for those (and any other available parameter) in the PayPal Standard Variables Documentation.
来源：https://stackoverflow.com/questions/30562581/what-do-the-src-and-sra-form-fields-for-paypal-ipn-html-form-do