Part II: Rules of Air Warfare#Chapter I: Domain of application: classification and marks. - Art. 8.
Art. 8. The exterior marks required by the regulations in force in each State shall be brought without delay to the knowledge of all the other Powers.
Modifications made in time of peace in the regulations requiring exterior marks shall be brought to the knowledge of all the other Powers before being put in force.
Modifications made in such regulations at the outbreak or in course of hostilities shall be brought by each Power to the knowledge of all the other Powers as soon as possible and at the latest when they are communicated to its fighting forces.