We define the States as:
Discovering = still adding scope (so don't trust the % Done)
Developing = scope is known (% Done is meaningful)
Measuring = all stories are Accepted (% Done = 100%), but we cannot say we are truly Done (e.g. need to run regression or performance tests, get customer signoff)
Done = Done
These definitions apply at the lowest portfolio item level, and then roll up to higher level. The higher level item should have the earliest State of its children.