Under FRACAS in the Calculate window, the MTBF Calculations page provides for applying different filters to the MTBF (mean time between failure) calculation to compute as many as 10 different variations of MTBF calculations. For example, you can compute the MTBF for the failures that occurred in a specified environment or under specific operating conditions. For more information, see MTBF (Mean Time Between Failures). By default, all calculations are cleared. You can click the Select All button or Clear All button to select or clear all calculations and then customize your selections from there. The following table describes the table columns on the MTBF Calculations page.