You can use task dependencies to relate tasks within or across projects as predecessors and successors.
By default you can create dependencies for any task in a workplan structure. You can limit task dependency creation to lowest-level tasks only by going to the Workplan Structure Information page and selecting Allow Dependencies Only for Lowest Tasks.
You create and maintain task dependencies through the Dependencies subtab of the Task Details page. You can create both intraproject dependencies (dependencies between tasks in the current working version of a workplan) and interproject dependencies (dependencies between tasks in the current working versions of separate project workplans).
When you create an intraproject dependency you must follow these rules:
You cannot create duplicate dependencies.
You cannot create circular dependencies between two or more tasks.
You cannot create tasks that depend upon themselves.
You cannot create a predecessor dependency from a task to a successor task if the task has subtasks that depend on the successor task.
You cannot create a dependency between tasks that are in the same hierarchical "path" from lowest task to highest task
You can create four types of task dependencies:
Finish to Start: Indicates that the predecessor task must finish before the successor task can start.
Start to Start: Indicates that the predecessor task must start before the successor task can start.
Finish to Finish: Indicates the predecessor task must finish before the successor task can finish.
Start to Finish: Indicates that the predecessor task must start before the successor task can finish.
You can also specify a lag value for the predecessor task. This value represents the number or fraction of days by which the successor task start or finish can be delayed with respect to the start or finish of the predecessor task. For example, if you enter three lag days for a finish to start dependency, the successor task starts three days after the predecessor has finished. You can enter a negative lag value.
Attention: If you are using Microsoft Office Project or another third party scheduling tool, you can also enter lag time in hours, minutes, or seconds. Note that for calculating and displaying lag time, Oracle Projects assumes that a day comprises eight hours.
The Gantt chart view of your workplan structure provides a comprehensive view of the task dependencies in your workplan and illustrates how they relate to each other. You can also review information about task predecessors using the flat list and hierarchical views of your workplan structure.
For more information about workplan structure views, see Viewing Workplans.
You cannot delete dependency relationships once the workplan version for which they have been created has been published.