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\part{Special files}
\textbf{This information is valid for Horde 3 only. See <a href="https://wiki.horde.org/Doc/Dev/SpecialFilesH4">Doc/Dev/SpecialFilesH4</a> for Horde 4 or <a href="https://wiki.horde.org/Doc/Dev/SpecialFiles">Doc/Dev/SpecialFiles</a> for Horde 5 and later.}

\begin{itemize}
\item \texttt{horde/lib/core.php}: This file
\begin{itemize}
\item sets some required PHP configuration settings


\item loads libraries required by all Horde applications


\item instantiates the global Browser object


\end{itemize}

\end{itemize}
There are several files with a special meaning that can be found in every Horde application:

\begin{itemize}
\item \texttt{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.


\item \texttt{lib/base.php}: This file is loaded from every script of the application. Its purpose is to:
\begin{itemize}
\item define some global constants


\item load \texttt{core.php}


\item initialize the <a href="https://wiki.horde.org/Doc/Dev/RegistryH3">Registry</a>


\item redirect to the login screen if the user is not authenticated and guest access is disabled


\item load common Horde libraries


\item initialize the <a href="https://wiki.horde.org/Doc/Dev/Notification">Notification System</a>


\item load common application specific libraries


\item initialize common global application specific objects and variables


\item start output compression


\end{itemize}

\item \texttt{lib/api.php}: This files defines and implements all methods that an application is exposing through the <a href="https://wiki.horde.org/Doc/Dev/RegistryH3">Registry</a> to the other Horde applications and the Horde RPC servers.


\item \texttt{lib/version.php}: This files defines a single constant: the application's version number.


\item \texttt{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 \texttt{horde/templates/common-footer.inc}.


\item \texttt{themes/screen.css}: This is a CSS file that defines all application specific style sheet rules.


\end{itemize}
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