Ok, I was told that a maintenance stretch lasts about 15secs and a developmental stretch can last for up to a minute. (I got told off after my gym exam for making my 'client' hold the stretches for too long
)
Also, a developmental stretch would be taken to a deeper level once the initial stretch reflex wears off and you would increase the stretch up to 3 times.
I'm not a Pump instructor (although I desperately want to be one) but as far as I can see, most of the stretches in the cooldown track appear to be maintenance stretches, although sometimes in the hamstring and glute/abductor stretches as well as in the lower back twists, we are told to take it deeper if we can (normally when the stretch is held for 32 counts in total), which would make it a developmental stretch.
Although in a gym environment, you could make any stretch developmental according to your client's needs, in my ETM we were told to make hamstring, adductor and chest stretches developmental when planning a class, as those are the muscle groups that are most likely to be particularly tight in the general public.
Who is your training provider cos I can't believe that this hasn't been covered 
Good luck anyway, and let us know how you get on 
Not tired are you???