...S&P Global Ratings assigned its '###' rating, with a stable outlook, to Watertown, Mass.' roughly $29.57 million general obligation (GO) school bonds. The city's full-faith-and-credit GO pledge secures the school bonds and existing GO debt, subject to Proposition 2 1/2 limitations. We rate the limited-tax GO debt on par with our view of Watertown's general creditworthiness because the ad valorem tax is not derived from a measurably narrower property tax base and there are no limitations on the fungibility of resources, supporting our view of the city's overall ability and willingness to pay debt service. Officials intend to use series 2022 bond proceeds to finance the town's elementary school project. Under our criteria, titled "Ratings Above The Sovereign: Corporate And Government Ratings--Methodology And Assumptions," published Nov. 19, 2013, on RatingsDirect, we rate Watertown higher than the sovereign because we think the city can maintain better credit characteristics than the nation...