Permanent establishment rules: fixed place, service duration and agency criteria determine taxable business presence across jurisdictions. The text defines permanent establishment as a fixed place of business carrying on an enterprise's activities, lists illustrative examples (management, branch, office, factory, warehouse, agricultural and extraction sites), and treats prolonged construction sites and aggregated service provision by personnel as creating a permanent establishment. It excludes preparatory or auxiliary activities (storage, display, purchasing, information gathering, processing by another enterprise) unless another fixed place is maintained for other purposes. Dependent agents with contract authority, habitual stock maintenance for delivery, or order securing can create a permanent establishment, while independent agents acting in the ordinary course are generally excluded; insurance collection through non-independent agents is also covered.