Permanent establishment: fixed place and agency tests determine whether an enterprise creates taxable nexus under the DTAA. A permanent establishment is a fixed place of business through which an enterprise carries on business, including management, branches, offices, factories, workshops, sales premises, warehouses for others and certain natural resource installations subject to temporal tests. Excluded are fixed places used solely for preparatory or auxiliary activities such as storage, display, purchase, information collection, advertising, or scientific research. Agency provisions treat an enterprise as having a permanent establishment where a non-independent agent habitually concludes contracts or maintains stock for regular delivery on behalf of the enterprise, while independent agents acting in the ordinary course do not create a permanent establishment.