I recently added a new item through IN-B and gave the unit of measure (stock/price/purchase) a type H.  I entered a PO for this part with a purchased quantity of 500.  The PO displayed the correct price.  I entered a SO for this part with a quantity of 100 and the SO displayed the correct price.  However, when I used AP-C to enter the invoice from the vendor, the type H formula did not compute (quantity/100 * price).  AP-C simply took quantity * price.  I manually changed the price in AP-C in order to pay the invoice correctly but the last cost and book value of this part are now way overstated.  
 
PO quantity = 500
UM price = $13.00
Total price = $65.00 (PO quantity/100 * price)
 
After receiving and paying the invoice the book value is $6500.00 instead of $65.00