Tax treaty definitions govern residence, enterprise, competent authority roles and mechanisms to resolve conflicting tax terms. Article 3 defines territorial scope and key treaty terms-person, company, enterprise, international traffic, competent authority, national, fiscal year and tax-noting tax excludes penalties. It directs that undefined terms adopt the applying State's domestic meaning, permits competent authorities to agree a common meaning where meanings differ or are indeterminate, and allows them to agree on source attribution in particular cases to eliminate double taxation.