Whether a Purchase Confirmation can be issued when purchasing finished goods that have already been manufactured

The transaction structure is as follows: A: Raw material supplier (supplies to B), B: Finished goods manufacturer and supplier (supplies to C), C: Simple exporter of finished goods (exports overseas). In this situation, I am inquiring whether it is possible for C to issue a Purchase Confirmation when purchasing finished goods from B. Since Article 18 of the Foreign Trade Act describes a Purchase Confirmation as a "document confirming the purchase of raw materials or equipment for the purpose of earning foreign exchange," I am asking whether a Purchase Confirmation can be issued even for the purchase of goods that have already been manufactured.