That is right, just as the title says. Once a transaction has been initiated it can not be returned.
(Let's just say they aren't the "Indian Giver Type")
The following is quoted from their website:
https://www.federalreserve.gov/paymentsystems/fedfunds_about.htm
The Federal Reserve Banks provide the Fedwire Funds Service, a real-time gross settlement system that enables participants to initiate funds transfer that are immediate, final, and irrevocable once processed. Depository institutions and certain other financial institutions that hold an account with a Federal Reserve Bank are eligible to participate in the Fedwire Funds Services. In 2008, approximately 7,300 participants made Fedwire funds transfers. The Fedwire Funds Service is generally used to make large-value, time-critical payments.
The Fedwire Funds Service is a credit transfer service. Participants originate funds transfers by instructing a Federal Reserve Bank to debit funds from its own account and credit funds to the account of another participant. Participants may originate funds transfers online, by initiating a secure electronic message, or off line, via telephone procedures.
The Fedwire Funds Service business day begins at 9:00 p.m. eastern time (ET) on the preceding calendar day and ends at 6:30 p.m. ET, Monday through Friday, excluding designated holidays. For example, the Fedwire Funds Service opens for Monday at 9:00 p.m. on the preceding Sunday. The deadline for initiating transfers for the benefit of a third party (such as a bank's customer) is 6:00 p.m. ET each business day. Under certain circumstances, Fedwire Funds Service operating hours may be extended by the Federal Reserve Banks.
For further information about Fedwire Funds Service, please see the Fedwire Services page on the Federal Reserve Financial Services website.
Last Update: February 19, 2014
Please keep in mind this is not intended for legal advice or anything of that nature. I am not a practicing attorney nor have I ever passed the BAR or any exam to legally give advice pertaining to the law. I do however enjoy looking at the content posted on the internet :)