NOTE 13: GUARANTEES AND INDEMNIFICATIONS
In conjunction with certain transactions, primarily the lease, sale or purchase of operating assets or services in the ordinary course of business, we may provide routine guarantees or indemnifications (e.g., environmental, fuel tax and software infringement), the terms of which range in duration, and often they are not limited and have no specified maximum obligation. As a result, the overall maximum potential amount of the obligation under such guarantees and indemnifications cannot be reasonably estimated. Historically, we have not been required to make significant payments under our guarantee or indemnification obligations and no amounts have been recognized in our financial statements for the underlying fair value of these obligations.
We provide guarantees on certain FedEx unsecured debt instruments aggregating $2.75 billion at May 31, 2013, jointly and severally with other affiliated companies in the FedEx consolidated group. In addition, we guarantee, jointly and severally with other affiliated companies in the FedEx consolidated group, FedEx's $1.0 billion revolving credit agreement, which backs its commercial paper program. At May 31, 2013, no commercial paper was outstanding and the entire $1.0 billion under the revolving credit agreement was available for future borrowings. The guarantees are full and unconditional and are required by the lenders since FedEx has no independent assets or operations.
Special facility revenue bonds have been issued by certain municipalities primarily to finance the acquisition and construction of various airport facilities and equipment. These facilities were leased to us and are accounted for as operating leases. We have unconditionally guaranteed $551 million in principal of these bonds (with total future principal and interest payments of approximately $708 million as of May 31, 2013) through these leases.