Sec. 4-806. Credit Quality Parameters
Commercial paper at the time of purchase must be rated A-1+ or the highest category by not less than two national rating services. The weighted average credit quality is to be no less than "AA" for the intermediate term investment pool and "A" for the long-term investment pool. In addition, the minimum acceptable credit quality at the time of purchase for individual investments shall be "AA" for the short-term pool, "BBB" for the intermediate pool and "B" for the long-term investment pool.