This excerpt taken from the NS 10-K filed Mar 15, 2005.
Critical Accounting Policies and Estimates
The preparation of financial statements in accordance with United States generally accepted accounting principles requires management to select accounting policies and to make estimates and assumptions related thereto that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates. The following summary provides further information about Valero L.P.s critical accounting policies and should be read in conjunction with Note 2 of the Consolidated Financial Statements, which summarizes Valero L.P.s significant accounting policies.