Exchange of information: obligation to share tax-related data to carry out tax laws and prevent tax evasion. Competent authorities shall exchange information necessary to implement the Agreement and domestic tax laws, including for prevention of fraud and tax evasion; such information must be treated as secret, with disclosure of transmitting-State secrets limited to persons or authorities involved in tax assessment, collection, enforcement, prosecution or appeals and usable only for those purposes, though usable in public court proceedings. Information may be exchanged spontaneously, routinely, or on request, and authorities shall agree routine lists; no obligation requires measures contrary to domestic law or practice, provision of unobtainable information, or disclosure of trade secrets or information contrary to public policy.