[[meta copyright="Copyright © 2007, 2008 Free Software Foundation, Inc."]] [[meta license="""[[toggle id="license" text="GFDL 1.2+"]][[toggleable id="license" text="Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled [[GNU_Free_Documentation_License|/fdl]]."]]"""]] An extensible system is one that enables extensibility. Enabling extensibility means providing non-privileged mechanisms to extend existing objects and to introduce new objects. UNIX is generally not an extensible system as it does not generally facilitate the hooking of system calls. For instance, there is no way to hook into the virtual file system. This has motivated the introduction of separate, parallel interfaces by both the GNOME and KDE projects to provide users a more integrated view of their objects.