Change or add parameters to an name-value-pair string sent to PayPal when confirming a checkout for review. Passes the nvpString and order object.

apply_filters("pmpro_get_express_checkout_details_nvpstr", string $nvpStr, MemberOrder $order);

Parameters

$nvpString

string

$order

MemberOrder

Source

File: https://github.com/strangerstudios/paid-memberships-pro/blob/master/classes/gateways/class.pmprogateway_paypalexpress.php