Modvat credit on glass containers allowed only if container cost is included in product value, factual determination required. Modvat credit for glass bottles and crates is allowed only if the cost of those packing materials or containers is included in the value of the final product; following the change from specific to ad valorem duty for aerated waters, each claim must be subject to factual examination to determine whether such inclusion exists, and pending cases should be decided on that basis.