In the System Settings page of the Database Properties of a version 6.7 database, you may see a Custom settings check box in the Scheduler area:
However, this same check box is not displayed in other databases. Why? This check box appears only if your database was converted to 6.7 from an earlier version and if some custom values were defined for the Scheduler. Starting with version 6.7, 4D no longer asks you to enter numerical values and just displays a ruler. However, 4D 6.7 still allows you to use your old custom settings which explains the presence of the check box.