The fund's primary investment strategy is to dedicate a minimum of 80% of its total net assets (inclusive of any borrowed capital for investment) to municipal bonds. These bonds are specifically chosen because they offer exemption from ordinary federal income tax, and often from particular state taxes as specified in the fund's objectives. Furthermore, a significant portion—typically at least 75% of its net assets—will be allocated to municipal obligations that possess an investment-grade credit rating at the point of acquisition.