Exchange of information expands mutual tax information sharing and compels use of information gathering measures including financial data. The Second Protocol substitutes Article 28 to require that competent authorities exchange foreseeably relevant information for administering and enforcing taxes, with strict confidentiality: information is secret and may only be used by authorised persons for assessment, collection, enforcement, prosecution, appeals or oversight, and may appear in public court proceedings. Contracting States need not contravene domestic laws, supply unobtainable information, or disclose trade secrets or information contrary to public policy; however, requested States must use their information gathering measures to obtain information even without domestic interest, and may not refuse requests solely because information is held by banks, financial institutions, nominees or fiduciaries or concerns ownership interests.