What is a discrete milestone?

Question

I know what a milestone is (this point of time in the project schedule where a major deliverable is done), but I don't know what a discrete milestone is, and what makes it different from any other milestone. Anyone care to explain the term?

Answer 1

The difference between a normal milestone and a discrete milestone is that the latter is fixed by a certain date. While normal milestones are set to take a place when a deliverable is done, a discrete milestone is set to take a place at a fixed point of time.

That fixed point of time is normally chosen based on the start or the finish date of a major deliverable (which is exactly the same as any other milestone), but the milestone will take place anyway on that date even if the deliverable did not finish or start at that date. An example is a discrete milestone that is set to take place on Monday, January 2nd, 2012 after a major deliverable X is finished. Now if deliverable X is not finished on January 2nd, 2012, the milestone will still take place.  

PS: None of the PM references clearly explain the meaning of a discrete milestone, so it's a good idea I had the chance to explain it myself.