...MEXICO CITY (Standard & Poor's) Sept. 22, 2015--Standard & Poor's Ratings Services assigned its '###+' issue-level rating to Banco Nacional de Comercio Exterior S.N.C.'s (Bancomext; foreign currency: ###+/Stable/A-2) proposed 10-year senior unsecured notes for an initial amount of up to $750 million. The bank will use them to extend the maturity profile of its liabilities and for asset and liability management purposes. The rating on the notes is the same as the issuer credit rating on Bancomext, which reflects our belief that the notes will rank equally in right of payment with all the bank's other obligations that are fully guaranteed by the federal government. The ratings on Bancomext reflect our opinion of an "almost certain" likelihood of extraordinary government support, resulting from our assessments of its "critical" role in the government's public policies and "integral" link to the government. As a result, our ratings and outlook on Bancomext are the same as those on Mexico (foreign...