Constraints set rules for scheduling a task based on relationships, dates and/or a combination of the two.

As Soon As Possible will adjust the start date of the task to the earliest possible date that the predecessor tasks will allow. If there are no predecessor tasks, it will automatically adjust to the start date for the project.

Finish No Earlier Than will adjust the task start date, if necessary, so that the schedule for the task does not finish prior to the constraint date specified.

Finish No Later Than will adjust the task start date, if necessary, so that the schedule for the task does not finish later than the constraint date specified.

Must Finish On will adjust the task start date so that it finishes on the constraint date specified.

Must Start On will adjust the task start date so that it starts on the constraint date specified.

Start No Earlier Than will adjust the task start date, if necessary, so that the schedule for the task does not start prior to the constraint date specified.

Start No Later Than will adjust the task start date, if necessary, so that the schedule for the task does not start later than the constraint date specified.

% of Resource Workday & Task Duration Based on Start & End Dates is a special constraint which can only be applied temporarily and automatically during the task start and end date data entry. It cannot be selected from the Constraint Type drop-down. It is temporary because once it is used it returns the task setting to a Must Start On constraint with the duration which was calculated from the start and end dates entered. It is often used to calculate the number of working days between two calendar dates.

"Must" or "No Later Than" constraint types can force a task into an impossible schedule. These constraints will override any conflict within the predecessor relationships and force the schedule based on the constraint date instead of the dependency relationship. These types of constraints may be necessary for planning events within which the date cannot be changed, but their use should be carefully planned with the understanding that the schedule for the task will never change without modification to the constraint type and/or date.

Constraint dates are seldom used in project scheduling templates because the dates never change without directly editing the task.

Online 10/17/2016