A milestone can be given a deadline.

If this deadline is enabled, the dated milestone becomes an "official" phase of the activity module, and the assessment strategy may use them for calculating late indicators.

Deadline cannot be set before project starts, nor overcome the project's end. Project end is considered as a built in phase, in addition of any dated milestone.

The list ordering in the GUI being an ergonomic facility, consistency of deadline sequence is not verified when moving milestones up and down. Step 2 will reinforce signalling about such inconsistencies.