Task Level Constraints

Modified on Thu, 21 Aug at 7:19 AM

The Linarc scheduler allows you to define constraints at the task level, giving you control over task start and end dates in addition to dependency rules. These constraints automatically adjust planned dates and take precedence if they extend past dependency-driven calculations.

Constraints are applied in addition to task dependencies.
Planned start and end dates auto-adjust based on the applied constraint.
Constraint-driven dates override dependency-based dates if they fall later than the calculated schedule.

To add flexibility, the scheduler supports a secondary constraint that works alongside the primary one. This enables you to define a permissible date range for task start and/or completion.

Primary Constraint Types

Each constraint consists of two elements: the constraint type and its associated date. For example, with a “Start On or After” constraint, you can specify the earliest date a task may begin. Some constraint types are flexible, allowing adjustments to planned dates, while others are rigid, requiring a task to start or finish exactly on the specified date—overriding manual inputs and dependency-based calculations. The scheduler allows the following types of primary constraints:

Constraint Type	Rule / Description	Flexibility
As Soon As Possible	Task should begin at the earliest time permitted by its dependencies.	Flexible
Start On	Task must begin exactly on the specified date, overriding manual/dependency-based planned start date.	Semi-Flexible
Start On or After	Task must not begin before the specified date, overriding manual/dependency-based planned start.	Semi-Flexible
Start On or Before	Task must begin no later than the specified date, overriding manual/dependency-based start.	Semi-Flexible
Finish On	Task must be completed exactly on the specified date, overriding manual/dependency-based planned end date.	Semi-Flexible
Finish On or Before	Task must be completed earlier than the specified date, overriding manual/dependency-based planned end.	Semi-Flexible
Finish On or After	Task must not be completed earlier than the specified date, overriding manual/dependency based planned end date.	Semi-Flexible
Mandatory Start	Task must begin strictly on the specified date, regardless of dependencies.	Non-Flexible
Mandatory Finish	Task must finish strictly on the specified date, regardless of dependencies.	Non-Flexible
As Late As Possible	Task begins at the latest time permitted by its dependencies.	Flexible

Once a constraint is applied, the planned start date or the end date is adjusted according to the constraint type and the date specified appropriately.

Secondary Constraints

In addition to a primary constraint, the scheduler allows you to set a secondary constraint. This provides greater flexibility when you want to define a valid date range for starting or finishing a task. Similar to the primary constraint, the planned dates are automatically adjusted to reflect the applied secondary constraint.

For example:

If you set “Start On or After” as the primary constraint and “Finish On or Before” as the secondary constraint, the task can begin any time on or after the specified start date, but it must be completed before the specified finish date.

The availability of secondary constraints depends on the type of primary constraint applied.

Primary vs. Applicable Secondary Constraints

Primary Constraint Type	Applicable Secondary Constraints
Start On or After	Start On or Before, Finish On or Before
Start On or Before	Start On or After, Finish On or After
Finish On or Before	Start On or After, Finish On or After
Finish On or After	Start On or Before, Finish On or Before
As Late As Possible	Start On or Before, Finish On or Before

No secondary constraints are available for primary constraint types outside the ones listed above.