First you need to create a custom calendar. To do so click on File-Calendar. Then, click on New, enter a name (e.g., SevenDayWeek), select "Create a new Base Calendar", and click OK.
Next, you need to use the custom calendar. Open the project (if it isn't alread), click on File-Information, select the "General" tab, select the appropriate "Base Calendar", and click on Close.
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