X Window System User's Guide for X11 R3 and R4 of the X Window System

Glossary

access control list	X maintains lists of hosts that are allowed access to each server controlling a display. By default, only the local host may use the display, plus any hosts specified in the access control list for that display. The list is found in /etc/Xn.hosts where n is the number of the display. The access control list is also known as the host access list.
active window	The window where the input is directed. With a “pointer focus” window manager such as twm, you must put the pointer in a window to make it the active window. The active window is sometimes called the focus window.
ASCII	American Standard Code for Information Interchange. This standard for data transmission assigns individual 7-bit codes to represent each of a specific set of 128 numerals, letters, and control characters.
background	Windows may have a background, consisting of either a solid color or a tile pattern. If a window has a background, it will be repainted automatically by the server whenever there is an Expose event on the window. If a window does not have a background, it will be transparent See also foreground.
background color	The color that determines the backdrop of a window, for example, on monochrome displays, the root window background color is gray.
background window	A shaded area (also called the root window) that covers the entire screen and upon which other windows are displayed.
binding	An association between a function and a key and/or pointer button. ...