AIX Version 4.3 Differences Guide

8.2.11 X Keyboard Extension
Prior to the introduction of the X Keyboard Extension (XKB) in X11R6, the core X
protocol was used for keyboard interaction. The core X protocol has a number of
limitations that make it difficult, or impossible, to properly support many common
varieties of keyboard behavior. The X Keyboard Extension provides capabilities
that are lacking, or cumbersome, in the core X protocol.
8.2.11.1 XKB Keyboard Extension Support for Keyboards
The X Keyboard Extension makes it possible to clearly and explicitly specify most
aspects of keyboard behavior on a per-key basis. It adds the notion of a keyboard
group to the global keyboard state and provides mechanisms to closely track the
logical and physical state of the keyboard. For keyboard-control clients, XKB
provides descriptions and symbolic names for many aspects of keyboard
appearance and behavior.
In addition, the X Keyboard Extension includes additional keyboard controls
designed to make keyboards more accessible to people with mobility
impairments.
8.2.11.2 XKB Extension Components
The XKB extension is composed of two parts:
• A server extension.
• A client-side Xlibrary extension.
The server portion of the XKB extension encompasses a database of named
keyboard components, in unspecified format, that may be used to configure a
keyboard. Internally, the server maintains a keyboard description that includes the
keyboard state and configuration (mapping). Keyboard is defined as the logical
keyboard device, which includes not only the physical keys, but also potentially a
set of up to 32 indicators (usually LEDs) and bells.
The keyboard description is a composite of several different data structures, each of
which may be manipulated separately. The individual components are shown in
Figure 45.
196 AIX Version 4.3 Differences Guide