Constraints

A constraint is a limitation placed on a project task to determine the start or end of the task. Constraints can take the form of fixed imposed dates for a task. For example, a project manager can assign a specific finish date for a task without allowing the dates to be determined by the planning process.
The following constraint types are available:
  • As soon as possible: This constraint schedules the task to the earliest possible time that the task can start, based on the existing project schedule. This constraint does not admit a fixed date.
  • Finish no later than: This constraint restricts the task to complete on or before a specified constraint date. You must specify the constraint date with this constraint.

As soon as possible

This is the default constraint type. When you create a project, all tasks are scheduled to start on the same date as the project start date. To specify different start dates for the elements, you must define dependencies between project tasks, or manually change the start dates to later than the project start date.

For a project task that is not dependent on any other task, that is, a task with no predecessor, the task start date is the same as the project start date. With this default constraint, you can change the task start date to a later date, that is, a date later than the project start date.

For a task that is dependent on some other task, that is, a task with one or more predecessors, the task start date is the next working day after the finish date of all its predecessor tasks.

The constraint date is not available for this constraint.

Finish no later than

When you apply this constraint to a task, you must specify the constraint date, that is the date by which the task must complete.

For a task with this constraint, you can specify a proposed finish date that is the same as or earlier than the constraint date.

If you specify the proposed finish date for the task to later than the constraint date, you are prompted to keep or break the constraint.
  • If you keep the constraint, no changes are made. The finish date change is rolled back to the original date.
  • If you break the constraint, the constraint changes to the default constraint 'As soon as possible'

When you apply constraints to a task with dependencies, if the constraint affects the schedule constraint of a dependent task, you can either keep the dependency and remove the constraint, or remove the dependency and apply the constraint.


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