Fedwire, the settlement system for Treasuries, is programmed to make bills disappear once they pass their maturity date.
Fedwire 是美国国债的结算系统，它被编程为在票据到期后消失。
英语百科
Fedwire
Formally known as the Federal Reserve Wire Network, Fedwire is a real-time gross settlement funds transfer system operated by the United States Federal Reserve Banks that enables financial institutions to electronically transfer funds between its more than 9,289 participants (as of March 19, 2009).