Maintenance window

http://en.wikipedia.org/wiki/Maintenance_window

In information technology and systems management, a maintenance window is a period of time designated in advance by the technical staff, during which preventive maintenance that could cause disruption of service may be performed.

The primary goal of maintenance is to avoid or mitigate the consequences of failure of equipment. This may be by preventing the failure before it actually occurs which Planned Maintenance and Condition Based Maintenance help to achieve

http://msdn.microsoft.com/en-us/library/cc144068.aspx

Within Microsoft System Center Configuration Manager 2007, maintenance windows (sometimes called service windows) provide administrators with a way to define a period of time that limits when changes can be made on the systems that are members of a collection.