NY -- Standard&Poor's CreditWire 10/16/97 -- Standard&Poor's today assigned its single-`B'-minus rating to Iron Mountain Inc.'s privately placed, Rule 144A $250 million senior subordinated notes due 2009. Standard&Poor's also assigned its single-`B'-plus bank loan rating to Iron Mountain's $250 million senior secured revolving credit facility due 2002. Standard&Poor's affirmed its single-`B'-minus rating on the company's $165 million senior subordinated notes due 2006 and its single-`B'-plus corporate credit rating. The ratings outlook remains positive. The bank facility is rated the same as the corporate credit rating. Although the facility derives strength from its secured position, based on Standard&Poor's simulated default scenario, it is not clear that a distressed enterprise value would