When I need to refer to the system in the abstract — rather than talking about any specific numbers — I use the
Area Category ID = AC.ID
Any Johnny.Decimal number is made up of the area/category before the decimal, then the ID after. So when I refer to
AC.ID, I just mean any number in your system.
Project Area Category ID = PRO.AC.ID
If you’re using a multiple-project system, the notation is expanded and becomes