[61] The occupation provisions may be conveniently summarized at this point. German territory situated west of the Rhine, together with the bridge-heads, is subject to occupation for a period of fifteen years (Art. 428). If, however, "the conditions of the present Treaty are faithfully carried out by Germany," the Cologne district will be evacuated after five years, and the Coblenz district after ten years (Art. 429). It is, however, further provided that if at the expiration of fifteen years "the guarantees against unprovoked aggression by Germany are not considered sufficient by the Allied and Associated Governments, the evacuation of the occupying troops may be delayed to the extent regarded as necessary for the purpose of obtaining the required guarantees" (Art. 429); and also that "in case either during the occupation or after the expiration of the fifteen years, the Reparation Commission finds that Germany refuses to observe the whole or part of her obligations under the present Treaty with regard to Reparation, the whole or part of the areas specified in Article 429 will be re-occupied immediately by the Allied and Associated Powers" (Art. 430). Since it will be impossible for Germany to fulfil the whole of her Reparation obligations, the effect of the above provisions will be in practice that the Allies will occupy the left bank of the Rhine just so long as they choose. They will also govern it in such manner as they may determine (_e.g._ not only as regards customs, but such matters as the respective authority of the local German representatives and the Allied Governing Commission), since "all matters relating to the occupation and not provided for by the present Treaty shall be regulated by subsequent agreements, which Germany hereby undertakes to observe" (Art. 432). The actual Agreement under which the occupied areas are to be administered for the present has been published as a White Paper [Cd. 222]. The supreme authority is to be in the hands of an Inter-Allied Rhineland Commission, consisting of a Belgian, a French, a British, and an American member. The articles of this Agreement are very fairly and reasonably drawn. [62] Art. 365. After five years this Article is subject to revision by the Council of the League of Nations. [63] The German Government withdrew, as from September 1, 1919, all preferential railway tariffs for the export of iron and steel goods, on the ground that these privileges would have been more than counterbalanced by the corresponding privileges which, under this Article of the Treaty, they would have been forced to give to Allied traders. [64] Art. 367. [65] Questions of interpretation and application are to be referred to the League of Nations (Art. 376). [66] Art. 250. [67] Art 371. This provision is even applied "to the lines of former Russian Poland converted by Germany to the German gage, such lines being regarded as detached from the Prussian State System."