The fund will normally invest at least 80% of its assets in, or derive at least 80% of its income from, securities that are exempt from regular federal income tax. The fund will invest up to 30% of its assets in securities that may subject the investors to federal alternative minimum tax. The fund invests at least 65% in debt securities rated BBB- or better or Baa3 or better by NRSRO designated by the fund's investment adviser, or unrated but determined by the fund's investment adviser to be of equivalent quality.