NY -- Standard&Poor's CreditWire 9/21/98 – Standard&Poor's today assigned its triple-'B'-plus rating to Vermont Education and Health Building Finance Agency's revenue bonds issued for Brattleboro Member Hospital (BMH), Vt. In addition, Standard&Poor's raised its rating on the agency's outstanding revenue bonds issued for BMH to triple-'B'-plus from triple-'B'. The outlook is stable. The assigned rating and the upgrade on BMH's bonds reflects: -- Limited direct competition within service area; -- Solid operating performance and financial flexibility; improved cash position; and -- Low cost provider. These factors are somewhat offset by BMH's small business base, a small active medical staff and concentrated payor mix with about 51% of revenues derived from government sources. BMH is