You will customize a base calendar to specify different working
hours on specific days or assign a day as non-working day.
In a project, you will have situations when you have to declare
a partial or full holiday other than the days specified in the base calendar.
Also, you might need to change a planned holiday to a working day due to business
need. This customization is called adding exceptions to a calendar.
Note: After
the calendar is associated to a project, you can customize it from the WBS
view.