Loads up information about any available payment gateways

Return value

Expected type: Array of arrays
Description: An array of information about available payment gateways. Keys are numeric, and each array has filename, code, valid_version, payment_class and display_class

• Checks the Sources directory for any files fitting the format of a payment gateway (Subscriptions-xxx.php).
• Loads each file to make sure it's valid.
• Includes each file and returns the function name and whether it should work with this version of SMF.