A set of four criteria, laid down for European Monetary Union by the Maastricht Treaty of 1993, that had to be met by a member state before it could adopt the euro. The criteria set limits to divergencies in inflation rates, and changes in exchange rates during the period leading up to union, and set maxima of 3 per cent for budget deficits, 60 per cent for the ratio of government debt to gross national product, and 2 percentage points for the excess of the long-term nominal interest rate over that of the three best-performing member states.