What is the expected behavior of the Must Finish On constraint in PPM/OWB?

Document ID : KB000012859
Last Modified Date : 14/02/2018
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Question:

What is the expected behavior of Must Finish On constraints in PPM/OWB?

Environment:
Applies to all supported PAS environments for specified releases.
Answer:

Must Finish On defines the date on which the task is required to finish.

To add a constraint to a task from within PPM:

1. In PPM, go to Home->Projects then click on the link for the project.

2. Click on the Tasks tab.

3. Click on the link for the task.

4. Select the 'Properties' tab and then click 'Constraints'.

5. Populate a date in one of the Constraints fields based on how you want the task to behave, then click Save and Return.

There are some factors that can prevent the task from finishing on the set constraint date:

One factor that can influence whether a Must Finish On constraint date is honored is the Actual Start Date. If the Actual Start Date is after the Must Finish On date, then the Finish date could be pushed out. Additionally, if the Actual Start date is earlier then the current Start Date of the task, it may cause the duration of the constraint to increase to honor both the Actual Start Date and Must Finish On constraints:

Example below:

  • Task Start Date: 10/31/16
  • Task Finish Date: 11/1/16
  • Duration: 2
  • Must Finish On Constraint: 11/8/16
  • Actual Start Date: 10/17/16

Results after autoscheduling:

  • The Task Start Date is moved back to the Actual Start Date of 10/17/16

In order to honor the Must Finish On constraint, the Task Finish Date is changed to 11/8/16, thus increasing the Duration of the task to 17 days.

Another factor that can influence whether the 'Must Finish On' constraint date is honored is the Start Date used in Autoscheduling.  See the task setup below as an example:

  • Task Start Date: 10/31/16
  • Task Finish Date: 11/1/16
  • Duration: 2
  • Must Finish On Constraint: 11/8/16

If the Autoschedule date is: 10/31/16, the Must Finish on Constraint is honored and task Finish Date is updated to 11/8/16. Since there are no constraints on the task other than the Autoschedule Start Date and Must Finish On Constraint, then any Autoschedule Start date up to and including 11/8 should allow autoschedule to honor the constraint.

However, if the Autoschedule date is set to: 11/9/16, the Must Finish On Constraint is not honored and the Finish date of the task is pushed out to 11/9/16. Any Autoschedule Start Date after 11/1 would push the task's start date past 11/1. The Autoschedule Start Date tells PPM that the user wants any task/assignment start/work to be moved to that date or later when there is no overriding constraint on the start. The Must Finish On constraint constrains the task's finish not it's start. So, in this scenario, if the user wanted the task to finish on 11/8/16 regardless of the Autoschedule Date then they could set a "Must Start On" constraint of 11/7/16 with the 2 day duration. 

Additional Note:

If more than one constraint is added, the most limiting constraint will be respected. Must Start On and Must Finish On field values are respected above the "no earlier than" and "no later than" constraints. Start date constraints are more important than end date constraints when performing a forward schedule, and end date constraints are more important than start date constraints when performing a backward schedule. 

Additional Information:

- Click here for information on all constraint types. Constraint types are found under the 'Edit Task Properties' section

- Click here for additional documentation on managing projects  Open Workbench (OWB)