International organizations — Privileges and immunities — Staff members — Former staff members — Exemption from taxation on salaries and emoluments received — Whether monthly pension payments exempt from Australian income tax — Construction of Section 6(1)(d), International Organisations (Privileges and Immunities) Act 1963 (Cth)

Treaties — Interpretation — Convention on the Privileges and Immunities of the Specialized Agencies, 1947 — Whether Australia required not to tax monthly pension payments received by former officer of specialized agency — State practice and preparatory work — The law of Australia