Article 89.
Poland undertakes to accord freedom of transit to persons, goods, vessels, carriages, wagons and mails in transit between East Prussia and the rest of Germany over Polish territory, including territorial waters, and to treat them at least as favourably as the persons, goods, vessels, carriages, wagons and mails respectively of Polish or of any other more favoured nationality, origin, importation, starting point, or ownership as regards facilities, restrictions and all other matters.
Goods in transit shall be exempt from all customs or other similar duties.
Freedom of transit will extend to telegraphic and telephonic services under the conditions laid down by the conventions referred to in Article 98.
Article 90.
Poland undertakes to permit for a period of fifteen years the exportation to Germany of the products of the mines in any part of Upper Silesia transferred to Poland in accordance with the present Treaty.
Such products shall be free from all export duties or other charges or restrictions on exportation.
Poland agrees to take such steps as may be necessary to secure that any such products shall be available for sale to purchasers in Germany on terms as favourable as are applicable to like products sold under similar conditions to purchasers in Poland or in any other country.
Article 91.
German nationals habitually resident in territories recognised as forming part of Poland will acquire Polish nationality ipso facto and will lose their German nationality.
German nationals, hovever, or their descendants who became resident in these territories after January 1, 1908, will not acquire Polish nationality without a special authorisation from the Polish State.
Within a period of two years after the coming into force of the present Treaty, German nationals over 18 years of age habitually resident in any of the territories recognised as forming part of Poland will be entitled to opt for German nationality.
