These firms include banks, non-bank credit card issuers and non-bank merchant acquirers, e-money issuers, etc. Enrich comprises airlines, banks, credit-card issuers, hotels and retailers around the world. Several IINs are well known, especially those representing credit card issuers. A cash advance is a service provided by most credit card and charge card issuers. EMV Certificate Authority issues digital certificates for payment card issuers. In Europe, the main issuers are banks. Visa was the last of the major credit card issuers to relax the signature requirements. Eventually Discover grew to become one of the largest credit card issuers in the U.S. Card issuers or sellers are not required to obtain a license. Note, these states explicitly require licensing for card issuers. EMV is the standard adopted by all major issuers of smart payment cards. Other important factors for collectors can be countries, issuers, and authors. This system allows for up to 4 card issuers in the market. The company typically ranks in the top 100 of patent issuers in the U.S. Many issuers are typically "orphaned".