This excerpt taken from the DRIV 10-K filed Mar 16, 2005.
Allowance for Doubtful Accounts. The preparation of financial statements requires management to make estimates and assumptions that affect the reported amount of assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Estimates are used in determining our allowance for doubtful accounts and are based on our historical experience and current trends. Management must make estimates of the uncollectability of our billed accounts receivable. Management specifically analyzes accounts receivable and historical bad debts, customer credit-worthiness, current economic trends and changes in our customer payment terms when evaluating the adequacy of the allowance for doubtful accounts. Significant management judgments and estimates must be made and used in connection with the allowance in any accounting period. Material differences may result in the amount and timing of our operating results for any period if management makes different judgments or utilizes different estimates.