Treaties — Special kinds of — Double taxation conventions — Income-Tax Convention between United States and Switzerland, 1951 — Meaning of “permanent establishment” provisions — Interpretation by United States Treasury Regulation — Effect of acquiescence in Regulation by Switzerland — The law of the United States of America.

Treaties — Interpretation of — Rules of — Conduct of the parties — Double Taxation Convention between United States and Switzerland, 1951 — Meaning of “permanent establishment” proviso — Interpretation by United States Treasury Regulation — Effect of acquiescence in Regulation by Switzerland — The law of the United States of America.