The Digital Certificate Access Server (DCAS) is a z/OS® TCP/IP server that you can use for enhanced logon solutions for z/OS applications. DCAS is part of several IBM® express logon solutions, such as Express® Logon Feature (ELF) and Web Express Logon (WEL), that work with IBM's host emulation products. DCAS provides a service for these solutions (with ELF, DCAS is needed only for the 3-tier solution) by providing them with z/OS user IDs and PassTickets for logon to host applications. A PassTicket is like a password. In addition, DCAS also provides an open interface and can be used by third-party express logon solutions to obtain user IDs and PassTickets for logon to z/OS applications.