The document discusses options for changing a ledger's functional currency in Oracle E-Business Suite. It explains that the functional currency is determined by the primary economic environment in which an entity operates. If this changes, the functional currency may need to change to avoid misstating foreign exchange gains and losses. The best options are to either reimplement the affected ledgers in the new currency or use rules-based software to change the functional currency while maintaining full history and correctly calculating gains/losses. Using a reporting currency or secondary ledger alone may still result in misstatements under GAAP or IFRS accounting standards if the primary ledger's currency is incorrect.