Where is stored changes in Item Cost through a Period from OPM Actual Cost?

Hello,

I'm setting up and testing Oracle OPM in nR12.2.7

For procedure my key user run in daily basis the Actual cost in order to track Items cost, have visibility of trend of production batches, etc. My Question is: Where can I query the difference between previous and currentactual cost? I set up Up Actual Cost based on Period Moving Actual Cost and I can calculated and validate using PAMC formula, but I need know if such changes in Actual Cost are recognized, and recorded in one table, form, etc

Thanks

Roberto