===============
 Special files
===============

**This information is valid for Horde 4 only. See `Doc/Dev/SpecialFilesH3`_ for Horde 3 or `Doc/Dev/SpecialFiles`_ for Horde 5 and later.**

.. _`Doc/Dev/SpecialFilesH3`: https://wiki.horde.org/Doc/Dev/SpecialFilesH3?referrer=Doc%2FDev%2FSpecialFilesH4
.. _`Doc/Dev/SpecialFiles`: https://wiki.horde.org/Doc/Dev/SpecialFiles?referrer=Doc%2FDev%2FSpecialFilesH4

* horde/lib/core.php: This file

  * sets some required PHP configuration settings

  * sets autoloading paths for Horde libraries

  * registers error handlers

There are several files with a special meaning that can be found in every Horde application:

* index.php: This script is loaded if a user enters an application. Usually this script doesn't have any functionality but simple loads the default view of the application, sometimes depending on the user's preferences.

* lib/Api.php: This files defines and implements all methods that an application is exposing through the `Registry`_ to the other Horde applications and the Horde RPC servers.

* lib/Application.php: This file defines information need to initialize the application and to interact with the Horde framework. It also defines the version number of the application.

* lib/Test.php: This file defines any application specific tests to run when using the Horde test script.

* templates/common-header.inc: This is the common page header template for all scripts of the application. All applications use the same page footer template horde/templates/common-footer.inc.

* themes/default/screen.css: This is a CSS file that defines all application specific style sheet rules.