(1) Income from immovable property may be taxed in the Contracting State in which such property is situated.
(2) The term "immovable property" shall be defined in accordance with the law of the Contracting State in which the property in question is situated. The term shall in any case include property accessory to immovable property, rights to which the provisions of general law respecting landed property apply, usufruct of immovable property and rights to variable or fixed payments as consideration for the working of, or the right to work, mineral deposits and other natural resources. Ships, boats and aircraft shall not be regarded as immovable property.
(3) The provisions of paragraph (1) shall apply to income derived from the direct use, letting, or use in any other form of immovable property, or from any extraction or exploitation of natural resources.
(4) The provisions of paragraph (1) and (3) shall also apply to the income from immovable property of an enterprise and to income from immovable property used for the performance of professional services.