The fund typically dedicates a minimum of 80% of its net assets (including any funds borrowed for investment) to municipal obligations. These investments are issued by or on behalf of U.S. states, territories, possessions, the District of Columbia, and their respective political subdivisions, agencies, or instrumentalities, with the interest income generally being exempt from regular federal income tax. While the fund's primary focus is on acquiring municipal obligations with maturities of ten years or more, it also has the option to invest in those with shorter maturities or earlier call provisions.