Prodcution Variance

Hi

Anybody could explain below queries. Basically Iam MM

Consultant. I need this information very urgent.

1.What is the actual cost in the production order ?Where

can i see in the system ?

2.What is the production variance ? When it will post into

the Material Ledger ?

3.What is the purpose that why we are maintaining

Cost center in the workcenter ?

4. What is workcenter category and activity type ?

5. What does month end closing do ?

Could anybody explain the steps with tcode.

Regards,

RRS.