Price Variance Moving Average

I am trying to figure out why we have dollars into Price Variance Moving Average and Gain/Loss Variance Account.  I looked around at manuals, etc.  and can not find an explanation for this account.  I also need to know how this affects the GL accounts. 

I checked into one of the transactions from the Landed Cost document and I can not figure out why only some of the dollars goes into the price Variance Moving Average and the rest goes to Inventory Warehouse.

Gain/Loss Variance Account is also a mystery as to how that number is calculated and then posted.

Could someone please explain these accounts to me?

Thank you.