Calendar Page
The Calendar Page allows you to specify how the system calculates around non-working times and dates.
To mark a holiday:
Select the date of the holiday on the calendar and click the "Nonworking time" radio button.
To mark an unusual scheduled day (for example a day that is only 5 hours long)
Select the date on the calendar and click "Non Default working time", then fill in the From: and To: time ranges for that date.
To return a date to it's default settings:
Select the date, then click "Use default"
graphic
For your convenience you can create a variety of different calendars. Perhaps your engineering crew works 60 hour weeks or 12 hours a day while your sales crew works 40 hours?
No problem, click "Add new..." and you can create your own calendar.
graphic
The easiest way is simply to name the calendar in the Name:  textbox, then copy an existing calendar by clicking Make a copy of "Calendar" calendar... and finally click OK. That will duplicate the original calendar which you can then edit.
The long way is..."Create a new base calendar" which creates a blank calendar where all dates are set to the default time, and weekends are marked as "non-working time". The system will then rely on you to create your own holidays.