The Payments System Risk or PSR policy is a program to control depository institutions' use of intraday Federal Reserve credit, commonly referred to as "daylight credit" or "daylight overdrafts." This Board of Governors web site (http://www.federalreserve.gov/paymentsystems/psr/default.htm) will provide you with the current policy, important information on the policy and press releases on proposed changes to the policy among other information.
The Federal Reserve System Discount Window site provides additional supporting information including overviews and guides to assist in complying with the PSR policy as well as contact information.