The Web offers the ability for card-issuing banks to provide cardholders with a much fuller portrait of every merchant, including its line of business.
The link that is Tweeted, emailed etc. leads to a mobile-optimized landing page that has information about the merchant, including location, hours, and pictures and more.
Milo's list of merchants includes a range of retailers, from BestBuy and Nordstrom to Midwestern regional department store Blain's Farm and Fleet.
But several merchants, including Ms. Beyn, are threatening to sue.
More than eight million merchants, including those on eBay, now use the service, among them Dell, United Airlines and Best Buy.
Meanwhile, credit card companies are pressuring merchants, including hotels, to adopt uniform security standards.
U.S. Bancorp processes credit card and other electronic payments for 90,000 large merchants, including some airlines.
The company has formed partnerships with several online merchants, including ShopNow.com and RMI.net.
These merchants include Mr. Harrison, who continues to run Ellwood Books online at ellwoodbooks.com.com
More than 15 merchants, including BarnesandNoble.com and SharperImage.com, will follow suit.
