How does the application of the lower-of-cost-or-market rule differ between U.S. GAAP and IFRS?

Both U.S. GAAP and IFRS require use of the lower-of-cost-or-market rule to value inventories.
However, the two sets of standards differ in two respects. First, U.S. GAAP defines market value as replacement cost, subject to a maximum and minimum amount. In contrast, IFRS uses net realizable value as the measure of the market value of inventory, and no upper or lower limits are imposed.
Second, under U.S. GAAP, if inventory is written down to a new, lower market value, this amount becomes the basis for that inventory. Future write-downs of the inventory use this new amount to compare with market value. However, under IFRS, write-downs of inventory can be reversed in later periods. That is, a gain is recognized when the value of the inventory goes back up.