The yard (known as the "international yard" in the United States) was legally defined to be exactly 0.9144 meter in 1959 under an agreement in 1959 between Australia, Canada, New Zealand, South Africa, the United Kingdom and the United States. In the UK, the provisions of the treaty were ratified by the Weights and Measures Act of 1963. The Imperial Standard Yard of 1855 was renamed the United Kingdom Primary Standard Yard and retained its official status as the national prototype yard.