Network logic alone cannot reflect all project situations. Sometimes activities must be accomplished according to specific dates rather than on dates determined by other activities in the project. To model dependence on specific dates, assign primary and secondary constraints to activities.
P6 Professional provides both hard and soft constraints. A hard constraint type prevents activities from being moved. In P6 Professional, the hard constraints available are Mandatory Start and Mandatory Finish. A soft constraint type does not prevent activities from being moved, but it can distort float. In P6 Professional, the soft constraints available are Start on, Start on or before, Start on or after, Finish on, Finish on or before, and Finish on or after.
Note: The expected finish date, typically applied to an activity by a primary resource, can also be taken into account when scheduling a project.
Select a constraint type below to view its description.
Start constraints
Finish constraints
Finish on or before constraint
Mandatory constraints
Late constraint
As late as possible constraint