Used in a sequence diagram, an activation shows the time period during which an object or actor is performing an action.
On an object lifeline, the activation rectangle sits on top of the lifeline. Align the top of the rectangle with the initiation time and the bottom with the completion time.
Indicate the time during which an object in a sequence diagram is performing an action
Glue the begin point and end point on the top and bottom of an Activation shape to connection points on the Object Lifeline shape.
Change the activation's initiation or completion time
Drag a begin point or end point on the Activation shape up or down on the Object Lifeline shape until the point corresponds with the time you want.
Name an activation and add other property values
Double-click the Activation shape when both the shape's endpoints are glued to connection points on an object lifeline, and then enter the information you want.