Permanent establishment rules define when a business presence or agent creates taxable presence under the treaty. Permanent establishment is a fixed place of business through which an enterprise's business is wholly or partly carried on, including places of management, branches, offices, factories, workshops and extraction sites; building sites, construction, assembly or installation projects and supervisory activities qualify when they continue beyond a specified duration. Exclusions cover facilities used solely for storage, display, delivery, stock maintenance for storage or processing, purchasing or information collection, and activities of a preparatory or auxiliary character. A person other than an independent agent who habitually concludes contracts on behalf of an enterprise will create a permanent establishment unless limited to excluded preparatory or auxiliary activities; independent agents acting in the ordinary course do not.