Capital gains taxation: source-based rules allocate tax to situs, permanent establishment, place of management, or residence. Article 13 prescribes that capital gains from alienation of immovable property are taxable in the State where the property is situated; gains from movable property forming part of a permanent establishment or pertaining to a fixed base are taxable in the State of that establishment or base; gains from ships and aircraft in international traffic are taxable in the State of the enterprise's place of effective management; shares of a resident company may be taxed in the company's State of residence; other gains are taxable only in the alienator's State of residence. 'Alienation' is defined broadly.