Over the course of a given project, often times, it is up to the project management team and or the project management team leader to make a determination that the previously determined and derived schedule may need to be modified and or tweaked in one way or another in order to accommodate one of more schedule events. This may be because a particular event is running behind schedule, or in other cases because a succeeding event’s timing has to e changed one way or another. However, when the project management team and or project management team leader seeks to initiate changes, it is important that they adhere to the previously determined schedule management plan. The schedule management plan is the document that determines the criteria for developing and maintaining the actual project schedule, and represents a subsidiary of the project management plan as a whole. This schedule management plan may be a highly formalized document, or it could be very informal in some cases as well.
This term is defined in the 3rd and the 4th edition of the PMBOK.