The term "fixed base regularly available to him" is not defined in the Convention or in the Income Tax Act . The application of Article XIV must therefore be determined on a case by case basis, giving effect to the intention of the contracting states. A literal or legalistic interpretation that might defeat their intention is to be avoided: J.N. Gladden Estate v. The Queen, [1985] 1 C.T.C. 163 (F.C.T.D.) at 166-167, quoted with approval in Crown Forest Industries Ltd. v. Canada, 1995 CanLII 103 (SCC), [1995] 2 S.C.R. 802 at 822.