1 EXHIBIT 23.15 CONSENT OF COUNSEL We hereby consent to the inclusion in Exhibits 5.1 and 8.1 to this Post-Effective Amendment No. 2 to Registration Statement on Form S-1 (File No. 33-90480) of our opinions dated May 25, 1995 with respect to the legality of the securities registered thereby and to certain United States federal income tax consequences, respectively, and to the references to Vinson & Elkins L.L.P. under the headings "Tax Aspects" and "Legal Opinions." In giving this consent, we do not admit that we are in the category of persons whose consent is required under Section 7 of the 1933 Act and the rules and regulations of the Securities and Exchange Commission promulgated thereunder. VINSON & ELKINS L.L.P. By: /s/ A. Winston Oxley --------------------- A. Winston Oxley for the Firm Date: June 13, 1996