...This report outlines Fitch Ratings' analytical framework for assessing the risks inherent in U.S. residential mortgage-backed securities (RMBS) transactions backed by newly originated, seasoned, re-performing and nonperforming residential mortgages. Fitch's rating approach considers the credit risks of the underlying collateral; the soundness of the credit enhancement (CE) and legal structures; and the quality of the financial and operational condition of the parties to the transaction....