This booklet explains the philosophy and methods of the Office of the Comptroller of the Currency (OCC) for supervising the largest and most complex national banks. These banks include large banks as designated by the Senior Deputy Comptroller for Large Bank Supervision in Washington, D.C. and may include midsize banks at the discretion of the Deputy Comptroller for Midsize and Credit Card Banks. This guidance also pertains to foreign-owned U.S. branches and agencies, and international operations of both midsize and large banks.1 When reviewing the international operations of national banks, examiners should also be guided by the Basel Committee's "Core Principles for Effective Banking Supervision.