In 2009, Ticketmaster started adoption of a "paperless" restricted ticketing, in which tickets could not be resold. Under this system, customers prove their purchase by showing a credit card and ID. The measure was taken in response to ticket scalping and resale markup of tickets on secondary markets and adopted during Miley Cyrus (2009) World Wonder Tour, although Ticketmaster first experimented it with AC/DC's Black Ice World Tour (2008–10). Ticketmaster has since changed the name of the system to "Credit Card Entry". The system requires large groups to enter together with the person who purchased tickets. Some events have Ticket Transfer which allows the tickets to change ownership and allow for tickets to be transferred through Ticketmaster's proprietary systems. These cannot be later resold or transferred via ticket exchanges such as StubHub.