A fixed dateA calendar date (associated with a schedule) that cannot be ... More imposed on a scheduleSee project schedule and see also schedule model. The timing... More activityA component of work performed during the course of a project... More or scheduleSee project schedule and see also schedule model. The timing... More milestoneA significant point or event in the project. An event of zer... More, usually in the form of a “start no earlier than” and “finish no later than” date. A point in time determined by external circumstances.