12 CFR § 210.30 - Payment orders.
(a) Rejection. A sender shall not send a payment order to a Federal Reserve Bank unless authorized to do so by the Federal Reserve Bank. A Federal Reserve Bank may reject, or impose conditions that must be satisfied before it will accept, a payment order for any reason.
(b) Selection of an intermediary bank. For an interdistrict transfer through the Fedwire Funds Service, a Federal Reserve Bank is authorized and directed to execute a payment order through another Federal Reserve Bank. A sender shall not send a payment order to a Federal Reserve Bank that requires the Federal Reserve Bank to send a payment order to an intermediary bank (other than a Federal Reserve Bank) unless that intermediary bank is designated in the sender's payment order. A sender shall not send to a Federal Reserve Bank a payment order through the Fedwire Funds Service that instructs use by a Federal Reserve Bank of a funds-transfer system or means of transmission other than the Fedwire Funds Service unless the Federal Reserve Bank agrees with the sender in writing to follow such instructions.
(c) Execution date and payment date. A sender shall not send a payment order through the Fedwire Funds Service that instructs a Federal Reserve Bank to execute the payment order or to pay the beneficiary on a funds-transfer business day that is later than the Fedwire Funds Service funds-transfer business day on which the order is received by the Federal Reserve Bank, unless the Federal Reserve Bank agrees with the sender in writing to follow such instructions.