Standard&Poor's Ratings Services' ratings on Newton, Mass.-based Government Properties Income Trust (GOV) reflect the company's modest financial profile, characterized by very low leverage, above-average debt service and fixed-charge coverage, and a substantially unencumbered property portfolio. However, the company's asset base, which consists of 55 office buildings leased primarily to government tenants, is small compared with those of other rated REITs, contributing to our view that GOV's business risk profile is fair. In addition, although its tenant credit quality is high, GOV's exclusive focus on government-leased buildings could limit its growth opportunities and access to equity capital over the longer term. As a result, our ratings reflect our expectation that debt levels will trend higher and fall more in