The utility is called Online Computer Library Center , or OCLC . The utility's database is of more than 40,000,000 bibliographic records is a union catalog of holdings for libraries from throughout the world. The database contains bibliographic information for materials published throughout the world and in many languages. Both of these systems facilitate borrowing materials from member libraries in the region, nationwide and worldwide. When an ILL request is made, the item is first searched in the OCLC bibliographic database to verify its existence and to ascertain which libraries hold the item.
All libraries holding the item in question are potential lenders.
Once lenders have been identified, a electronic ILL request is submitted to them through the OCLC system. To increase the chance of getting the item, the request is usually sent to five potential lenders. This way there is a better chance of getting request filled. The potential lenders that are contacted receive the request in the sequence specified in the request. For instance, most libraries do not loan reference books, rare books, or multi-volume sets.