Strategy. The fund invests mainly in bonds (including general obligation bonds, revenue obligation bonds, and tender option bonds) that pay interest that is exempt from federal income tax (but that may be subject to federal alternative minimum tax (AMT)), are a combination of below-investment-grade (sometimes referred to as junk bonds) and investment-grade securities, and have intermediate- to long-term maturities (i.e., three years or longer). Under normal circumstances, the fund invests at least 80% of its net assets in tax-exempt investments. Such tax-exempt investments in which the fund invests are issued by or for states, territories or possessions of the United States or by their political subdivisions, agencies, authorities or other government entities, and the income from these investments is exempt from … Show more… The fund invests mainly in bonds (including general obligation bonds, revenue obligation bonds, and tender option bonds) that pay interest that is exempt from federal income tax (but that may be subject to federal alternative minimum tax (AMT)), are a combination of below-investment-grade (sometimes referred to as junk bonds) and investment-grade securities, and have intermediate- to long-term maturities (i.e., three years or longer). Under normal circumstances, the fund invests at least 80% of its net assets in tax-exempt investments. Such tax-exempt investments in which the fund invests are issued by or for states, territories or possessions of the United States or by their political subdivisions, agencies, authorities or other government entities, and the income from these investments is exempt from federal income tax. This investment policy cannot be changed without the approval of the funds shareholders. Interest income from private activity bonds may be subject to federal AMT for individuals. As a policy that cannot be changed without the approval of fund shareholders, the fund cannot include these investments for the purpose of complying with the 80% investment policy described above. The Investment Manager may consider, among other factors, credit, interest rate and prepayment risks, as well as general market conditions, when deciding whether to buy or sell investments. Show less