Using the Precedent Viewer  

While links between activities define the product flow and can be visualized with a PERT chart, precedence constraints define the activity flow and can be visualized with the Precedent Viewer. The Precedent Viewer relies on the same visualization features as the PERT chart and most of the options you set for the PERT Chart in Tools > Options > Digital Process for Manufacturing > PERT Chart (e.g., straight or orthogonal links) apply to the Precedent Viewer.

Note that the PERT and Precedent Viewers are separate viewers; for the same process, node positions and expanded states can differ within each viewer.

Precedence constraints between activities can be deleted within Precedent Viewer.  Right-click on the precedent constraint (i.e., the arrow between the two activities) and select Delete Constraint. If more than one precedence constraint is selected, the command Delete Constraint entry in the context menu is also deactivated.

Link Activities and Link Child Activities are available in the PERT, Product Flow and normal 3D Viewer only. The commands are disabled for all the viewers where control flows cannot be viewed, such as the Precedent Viewer and AST Editor.

Open the Precedent Viewer

1. To launch the Precedent Viewer, click Open Precedent Viewer in the Data Views toolbar.

2. Select the Process node in the PPR tree:

   The precedence constraint chart for the selected process is displayed. A precedence constraint between two activities is indicated by an arrow, as shown in the example below:

   In this example, the Quenching activity has a precedence constraint on the Heating activity. If you put your mouse over the arrow, a tooltip appears stating that Heating.2 Precedes Quenching.2.

   Activities that are parent nodes having child activities are indicated by a plus (+) symbol in the upper right corner, as shown below:

   The plus (+) symbol represents a hotspot that can be clicked to expand the selected node and display its children inside it, as shown here:

   When expanded, the bordered box for the selected activity displays a minus (-) symbol in place of the plus (+)  symbol. Click the minus (-) symbol to collapse the node back to its previous state.

About Precedence Constraints and Hidden Child Activites

Because child activities can be hidden, symbols are used to indicate when one or more children of a particular node have precedence constraints on another activity:

	The TypeA activity has a precedence constraint to a child of the Hardening activity.
	A child of TypeA has a precedence constraint on the Hardening activity.
	A child of TypeA has a precedence constraint on a child of the Hardening activity.