In this case, the preamble is not helpful. It is not suggested that the facts of this case give rise to any issue of fiscal evasion, and the avoidance of double taxation is not an objective of Article XIV. On the contrary, Article XIV specifically contemplates the possibility that income from independent personal services may be taxed in both countries. For example, income from independent personal services provided in Canada by a resident of the United States may be taxed in both countries to the extent it is attributable to a fixed base in Canada. In such a case, the burden of double taxation is avoided by a tax credit as described in Article XXIV