The investment seeks a high level of current income exempt from federal individual income tax. The fund invests principally in a portfolio of municipal obligations issued by states and state agencies, local governments and their agencies, and by United States territories and possessions. It invests in obligations and participations in obligations of any credit quality. The fund may invest in municipal obligations of any maturity, but seeks to maintain a portfolio of investments having a dollar-weighted average effective duration of normally one to ten years.