terminals explore the network (the local broadcast domain) using the X Display Manager Control Protocol to generate a list of available hosts that are allowed as clients. One of the client hosts should run an X display manager. A limitation of X terminals and most thin clients is that they are not capable of any input or output other than the keyboard, mouse, and display. All relevant data is assumed to exist solely on the remote server, and the X terminal user has no methods available to save or load data from a local peripheral device. Dedicated (hardware) X terminals have fallen out of use; a PC or modern thin client with an X server typically provides the same functionality at the same, or lower, cost. Limitations and criticism The Unix-Haters Handbook (1994) devoted a full chapter to the problems of X. Why X Is Not Our Ideal Window System (1990) by Gajewska, Manasse and McCormack detailed problems in the protocol with recommendations for improvement. User interface issues The lack of design guidelines in X has resulted in several vastly different interfaces, and in applications that have not always worked well together. The Inter-Client Communication Conventions Manual (ICCCM), a specification for client interoperability, has a reputation for being difficult to implement correctly. Further standards efforts such as Motif and CDE did not alleviate problems. This has frustrated users and programmers. Graphics programmers now generally address consistency of application look and feel and communication by coding to a specific desktop environment or to a specific widget toolkit, which also avoids having to deal directly with the ICCCM. X also lacks native support for user-defined stored procedures on the X server, in the manner of NeWSthere is no Turing-complete scripting facility. Various desktop environments may thus offer their own (usually mutually incompatible) facilities. Computer accessibility related issues Systems built upon X may have accessibility issues that make utilization of a computer difficult for disabled users, including right click, double click, middle click, mouse-over, and focus stealing. Some X11 clients deal with accessibility issues better than others, so persons with accessibility problems are not locked out of using X11. However, there is no accessibility standard or accessibility guidelines for X11. Within the X11 standards process there is no working group on accessibility; however, accessibility needs are being addressed by software projects to provide these features on top of X. The Orca project adds