If respondent had intended a contrary result, he should have made his intention clearer by setting out the exclusion of interest and taxes during construction as an express condition in the Terms Letters. As an example of the binding effect of an express condition in the terms letters, see Chicago, Milwaukee, St. Paul & Pacific R. Co. v. United States, 404 F.2d 960, 969-972 (Ct. Cl. 1968), where the taxpayer was held to be bound by the RATES OF DEPRECIATION set forth in the terms letters. We also reject respondent's argument that because petitioner excluded amounts attributable to interest and taxes during construction as part of its depreciable basis in schedules it submitted with respect to its election of certain treatment under section 94 of the Technical Amendments Act of 1958, Pub. L. 85-866, 72 Stat. 1606, or because petitioner did not claim deductions based on the inclusion of such amounts in its submitted returns over the years, petitioner is estopped