Cost Rollup in Periodic Average Costing

In standard costing you have to  enter all costs and perform cost rollup in a user defined cost type like Pending first and then do a standard cost update to Frozen.

What is the process for periodic avaerage costing - do you enter costs in a user defined cost type say PAC_RATES  , do a rollup there and then enter the costs manually(avarge cost update) in the periodic average cost (PAC) ?

Thanks

rahul