Permanent establishment: fixed business presence and agent activities determine taxable nexus and exclusions under the treaty. A permanent establishment is a fixed place of business through which an enterprise carries on business, including offices, branches, factories, workshops, sales outlets, warehouses providing storage for others, farms and places of natural resource extraction. Construction sites and service-provision through personnel constitute a permanent establishment only when activities exceed prescribed duration thresholds. Exclusions cover solely preparatory or auxiliary activities and limited uses of premises. Dependent agents who habitually conclude contracts, maintain delivery stocks, or secure orders predominantly for the enterprise create a permanent establishment, whereas independent agents acting in the ordinary course of business do not.