The parliamentary resolution requires the Royal Union Flag to be flown alongside the flag of Canada (if there are at least two flag poles available) at federal government buildings, federally-operated airports, military installations, at the masthead of Royal Canadian Navy ships within Canadian waters, and other appropriate establishments on Commonwealth Day, Victoria Day (the monarch's official birthday in Canada), 11 December (the anniversary of the enactment of the Statute of Westminster 1931), and when otherwise instructed to do so by the National Defence Headquarters. The Royal Union Flag may also be formally flown alongside the flag of Canada at federal locations in Canada in relation to ceremonies, anniversaries, and other events relating to the Canadian Armed Forces, or other forces in the Commonwealth. Formal usage of the Royal Union Flag on federal property is permitted only when two or more flag poles are present, to ensure the flag of Canada is not removed.