Automated Clearing House (ACH) is both direct debit and direct credit actually. Commercial transaction fees are $0.22 ea at my bank normally the recipient will absorb the fee. e.g.; Online credit card payments, etc. A USA based affiliate program (or one with a USA bank account) could pay USA based affiliates ACH or use a fee for service USA based payment processor to do the same. It is used by domestic USA Federal Reserve member banks -- that is the clearinghouse.

It is just funds transfer between USA (only) Banks.

Single Euro Payments Area (SEPA) is similar in nature and scope albeit newer -- ACH has been available for over 10 years in the USA.