Hi jaisree
A Pool capacity is one with several individual capacities.
Pool capacity is created to maintain the constraint mapping in APO
For eg, if you say, if your total manpower capacity is 10 hours per day wherein the labour available hours is 8 hours, then obviously the capacity of the work center per day is only 8 hours and not 10 hours even though machine is ready for working, it produces a constraint of 2 hours for want of manpower.
If you are working with both labour capacity and machine capacity, it is pre-requisite that both the capacities needs to get translate into APO (whether PDS or PPM).
Regards
virender