Book:OTRS 3.0 - Admin Manual/Chapter 8/1

Some functions in OTRS, like escalations and automatic unlocking of tickets, depend on a proper configuration of business hours, time zones and holidays. You can define these via the SysConfig interface, in Framework > Core::Time. You can also specify different sets of business hours, holidays and time zones as separate 'Calendars' in Framework > Core::Time::Calendar1 through Framework > Core::Time::Calendar9. Calendars can be defined by queue settings, or on SLA levels. This means that, for example, you can specify a calendar with 5 x 8 business hours for your 'standard' SLA, but create a separate calendar with 7 x 24 support for your 'gold' SLA; as well as set a calendar for your 'Support-USA' queue with a different time window than your 'Support-Japan' queue. OTRS can handle up to 99 different calendars.

Business Hours
Set up the working hours for your system in SysConfig Framework > Core::Time::TimeWorkingHours, or for your specific calendar in the calendar's configuration. OTRS can handle a granularity of one hour. Checking the marks in the boxes 8, 9, 10 ... 18 corresponds with business hours of 8 AM - 6 PM.

Only during business hours can tickets escalate, notifications for escalated and pending tickets be sent, and tickets be unlocked.

Fixed date holidays
Holidays that are on a fixed date every year, such as New Year's Day or the Fourth of July, can be specified in TimeVacationDays, or in the corresponding section for the calendars 1-9.

Tickets will not escalate nor get unlocked on dates defined in TimeVacationDays.

TimeVacationDaysOneTime
Holidays such as Easter that do not have a yearly fixed date but instead vary each year, can be specified in TimeVacationDaysOneTime.

Tickets will not escalate and will not be unlocked on dates defined in TimeVacationDaysOneTime.