You can create a Value Specification Action through an Activity Diagram or a Modeler pane.
To create a value specification action through an activity diagram:
1. On the Activity Diagram toolbar, click the arrow in the split button that is to the right of the Accept Event Action button, click the Value Specification Action button, and then on the Activity Diagram, click in free space or within an Activity Partition, Interruptible Activity Region or Structured Activity Node.
2. Type the name of the Value Specification Action, and then press the Enter key.
Modeler creates the Value Specification Action and on it creates the Result Pin output pin.
To create a value specification action through a Modeler pane:
1. In a Modeler pane, right-click the Activity or Structure Activity Node that is to own the Value Specification Action, point to New, point to Action Node, and then click Value Specification Action.
2. Type the name of the Value Specification Action, and then press the Enter key.
Modeler creates the Value Specification Action and on it creates the Result Pin output pin.
Accept Event Action button, click the 
Value Specification Action button, and then on the Activity Diagram, click in free space or within an Activity Partition, Interruptible Activity Region or Structured Activity Node.