NEW YORK -- Standard&Poor's CreditWire Feb 24, 1999 – Standard&Poor's today assigned its double-'A'-minus/'A-1'-plus to District of Columbia, D.C.'s $10.35 million revenue bonds series 1999, issued for Association of American Medical Colleges. The double-'A'-minus rating reflects: -- The association's monopoly on the services it provides, specifically medical school entrance testing and medical school accreditation; -- Continued generation of healthy operating surpluses; and -- Significant financial strength in the form of unrestricted fund balances. A higher rating is precluded by a moderately high debt burden that has increased in tandem with an increase in unrestricted resources as well as the concentrated nature of Association of American Medical Colleges' activities and revenue, which are all health-related. All bonds