Set categories for reporting particular categories of tasks beyond making them milestones.
For example, tasks which represent the go live date for new implementations could have a "Go Live" task type for reporting on the "Go Live" tasks across multiple projects.
Enable the TASK TYPES ADD-ON in PI administration:
Then hit the configure button:
The Task Type feature is most often used in conjunction with the rate flow function:
This rate flow is snipped from the bottom of a Contract.