36. A
functional airspace block ð that extend across the
airspace under the responsibility of more than one Member State ï shall only be established by ð joint designation ï mutual agreement between all the Member States and Ö ,as well as Õ , where appropriate, third countries who Ö that Õ have responsibility for any part of the
airspace included in the functional
airspace block ð The joint designation by which the functional
airspace block is established shall contain the necessary provisions concerning the manner in which the block
...[+++]can be modified and the manner in which a Member State or, where appropriate, a third country, can withdraw from the block, including transitional arrangements ï.