In Matter of Speno v. Gallman (35 N.Y.2d 256, 319 N.E.2d 180, 360 N.Y.S.2d 855 [1974], the Court addressed the language "sources within the state" (former Tax Law 632) in relation to the taxation of the income of the nonresident president of a company with offices in New York and abroad. The Court endorsed a "refinement" of the Attorney General's 1919 "place of performance" opinion. (Speno at 259.) That is, the Court accepted the Department's interpretation of the Tax Law in the convenience test, and held that "sources within the state" does not simply mean "place of performance." Rather, it calls for a more complicated analysis that takes into consideration why work is performed out of state. The decision in Matter of Zelinsky v. Tax Appeals Trib. of State of N.Y. (1 N.Y.3d 85, 801 N.E.2d 840, 769 N.Y.S.2d 464 [2003], cert denied 541 U.S. 1009, 124 S. Ct. 2068, 158 L. Ed. 2d 619 [2004]), which rejected challenges to the convenience test on federal due process and Commerce Clause grounds, was premised on the conclusion in Speno that the convenience test is a valid interpretation of the Tax Law.