Constraint
A constraint controls the start or end date of a WBS item and the degree to which that WBS item can be rescheduled.
Every WBS item has a type of constraint applied to it. The constraint types are categorized as:
• Flexible constraints: Planon ProCenter can change the start or end date of a WBS item. This type of flexible constraint is the default constraint type that is set for all WBS items.
• Inflexible constraints: A WBS item must start or end on a certain date. These constraints are also called hard constraints.
• Semi-flexible constraints: A WBS item has a start or an end date boundary. However, Planon ProCenter has the flexibility to change the start or end date of a WBS item.
For a description of the various constraint types used in combination with the constraint start or end date in Projects , see Constraint fields
 | A constraint can be set only on a start date or an end date for a WBS item and not on both simultaneously. |