X11

The current release of the X Window System is formally named "X WINDOW SYSTEM, Version 11, Release 6." Generically, X11 refers to the current code modules and libraries that compose the interface to the X Windows environment, and the runtime library that supports its proper execution. For more information on obtaining access to this code, visit the URL listed below.

URLs:

X11

The page at the X Consortium that describes the current release of the X Window System, along with pointers to various ways to obtain this information. According to this page, the software in this release is not in the public domain, but is freely available. No license is required and there are no royalties. Vendors are actively encouraged to base products on this software and on the standards defined by the X Consortium.