Under normal circumstances, the Fund invests at least 80 percent of its investable assets in municipal bonds of varying maturities whose income is exempt from federal income taxes. The term investable assets refers to the Funds net assets plus any borrowings for investment purposes. The Funds investable assets will be less than its total assets to the extent that it has borrowed money for non-investment purposes, such as to meet anticipated redemptions. For purposes of this policy, such municipal bonds include as zero coupon bonds, variable rate demand obligations, short term municipal notes, tax-exempt commercial paper, municipal lease obligations, municipal general obligation bonds, municipal revenue bonds, municipal bonds, floating and variable rate bonds, the interest on which is subject to the federal alternative minimum tax (AMT), pre-refunded and escrowed to maturity bonds, municipal cash equivalents, private activity bonds and municipal mortgage-backed and asset-backed securities, including auction rate securities and municipal bonds restricted from sale and also include other investments (including derivatives) with similar economic characteristics.