A milestone is a significant point or landmark in your project. Milestones are created as tasks with zero duration and are visualized with diamond shape. The milestone’s shape and color are customizable. Additionally, text can appear to the left, right, top, or bottom of the milestone marker. To create a milestone, you can use the Duration property of the Task class and set its value to zero.

To create a milestone at design time, follow the steps below:

1. Select the GanttView control and click on its smart tag to open the C1GanttView Tasks menu.
2. Select Edit Tasks. The C1GanttView.Tasks Collection Editor appears.
3. Click Add to add a task to the Members list.
4. Enter the Name, Start date and Finish date for the task.
5. Set the Duration to 0.