While the actual length of a credit card number varies by the credit card company it must follow a specific identification protocol as outlined by ISO.
ACH payments are electronic payments that are created when the customer gives an originating institution, corporation, or other customer (originator) authorization to debit directly from the customer's checking or saving account for the purpose of bill payment.
The Automated Clearing House (ACH) is the primary system that agencies use for electronic funds transfer (EFT). The regulations for ACH are in 31 CFR Part 210. Those regulations define both the rights and liabilities of all the people involved in the ACH system: government agencies, Federal Reserve banks, financial institutions, and the public.