Someone

			<route name="directory" pattern="^/directory" module="Directory" action="Index">
				<routes>
					<route name=".country" pattern="^/{iso_id:(AU|CA|US)}" action="Country">
						<route name=".state" pattern="^/{region:[A-Za-z]{2,3}}" action="Region">
							<route name=".city" pattern="^/{city:[A-Za-z_0-9]+}" action="City">
								<route name=".location" pattern="^/{location:[A-Za-z_0-9]+}" action="Location" />
							</route>
						</route>
					</route>
					<route name=".country" pattern="^/(iso_id:\S+)" action="Country">
						<route name=".city" pattern="^/{city:[A-Za-z_0-9]+}" action="City">
							<route name=".location" pattern="^/{location:[A-Za-z_0-9]+}" action="Location" />
						</route>						
					</route>
				</routes>
			</route>