Q - What is the difference between these two fields in the IMINVTRX table? 

INV_TRX_NEW_UN_COST

INV_TRX_NEW_AVG_COST

Periodically, we lower the average cost for closeouts and make a G/L entry for the loss in value. I am trying to find the historical write-downs by SKU and thought using the difference between the IMINVTRX new and old costs might be a way to achieve that goal. Using the difference between INV_TRX_NEW_AVG_COST and INV_TRX_OLD_AVG_COST for the package IM isn't yielding the desired result.

A - Let’s use an example of ITEM# ABC, which has quantity of 10 on hand at the moment. The old average cost is $10.

Let’s say we are going to receive 10 units of item ABC at $11. This is how the system calculates it:

INV_TRX_NEW_UN_COST = $11
INV_TRX_NEW_AVG_COST = (($10 * 10) + ($11 * 10)) / (10 + 10) = $10.50