Working with Flexible and Inflexible Constraints

There are three levels of flexibility associated with task constraints: flexible, moderately flexible, and inflexible.

Flexible Constraints

The flexible constraints are As Soon As Possible and As Late As Possible. These constraints work with task dependencies to schedule a task as soon or as late as the task dependency and other scheduling considerations will accommodate. These default constraints allow Microsoft Project maximum flexibility in calculating start and finish dates for the tasks. For example, a task with an ASAP constraint and a finish-to-start dependency is scheduled as soon as the predecessor task finishes.

Moderately Flexible Constraints

The moderately flexible constraints (Start No Earlier Than, Start No Later Than, Finish No Earlier Than, and Finish No Later Than) have a range of dates to work within. That is, the task is restricted to starting or finishing before or after the date you choose, which provides some room for flexibility, even though a date is in place. For example, a task with a Start No Later Than constraint for November 14 and a finish-to-start dependency to another task can begin any time its predecessor is finished up until November 14, but it cannot be scheduled after November 14.

Inflexible Constraints

The inflexible constraints, Must Start On and Must Finish On, have an absolute single date that the schedule must accommodate, which means that other scheduling considerations must fall by the wayside if necessary to meet this date. By default, constraints take precedence over task dependencies when there's a conflict between the two. For example, a task with a Must Finish On constraint for April 30 and a finish-to-start dependency to another task is always scheduled for April 30, regardless of whether the predecessor finishes on time.


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  • angelico
    Why us inflexible constraint microsoft project?
    21 days ago

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