12 CFR 270.2 - Definitions.
(a) The term obligations means Government securities, U.S. agency securities, bankers' acceptances, bills of exchange, cable transfers, bonds, notes, warrants, debentures, and other obligations that Federal Reserve banks are authorized by law to purchase and sell.
(b) The term Government securities means direct obligations of the United States (i.e., U.S. bonds, notes, certificates of indebtedness, and Treasury bills) and obligations fully guaranteed as to principal and interest by the United States.
(c) The term U.S. agency securities means obligations that are direct obligations of, or are fully guaranteed as to principal and interest by, any agency of the United States.
(d) The term System Open Market Account means the obligations acquired pursuant to authorizations and directives issued by the Committee and held on behalf of all Federal Reserve banks.