+At start the interpreter does not know any black box.
+If you type \texttt{'help packages'}, which is
+the third form of the \texttt{help} command, you get :
+\begin{verbatim}
+> help packages
+user
+ workspace
+\end{verbatim}
+
+which means that the interpretor only knows one package
+(library of black boxes) called \texttt{user}
+and which contains a black box called \texttt{workspace}.
+The \texttt{user} package is an internal package of the interpreter,
+which stores user-defined black box types.
+At start, it already contains
+one box, called \texttt{workspace}.
+\texttt{workspace} is a special type of black box,
+called complex black box, whose purpose is
+to store other black boxes.
+Any black box you create in \bbStudio is stored
+in \texttt{workspace}
+(this will be explained in details in sections
+\ref{bbi-writing-scripts} and
+\ref{bbi-more-on-complex-black-boxes}).
+
+If you type \texttt{'help workspace'}, you get :
+\begin{verbatim}
+> help workspace
+ Complex Black Box <user::workspace>
+ User's workspace
+ By : bbtk
+ Category(s) : complex box;
+ * No inputs
+ * No outputs
+ * No boxes
+\end{verbatim}
+
+In the text displayed,
+the \texttt{user::} prepended to the name \texttt{workspace}
+means that the box \texttt{workspace}
+belongs to the \texttt{user} package.
+Then comes a description and three lines which
+tell that \texttt{workspace} does not have any input
+nor output nor boxes yet.
+
+In order to let the interpreter know of some black boxes,
+you must load another package.
+The \texttt{std} package is the ``standard'' package,
+which contains basic useful black boxes.
+
+To load it, type :
+\begin{verbatim}
+> include std
+\end{verbatim}
+
+Then if you type :
+\begin{verbatim}
+> help packages
+\end{verbatim}
+
+you get something like :
+
+\begin{verbatim}
+
+ std
+ ASCII : ascii codes sequence to string - string to ascii...
+ Add : Adds its inputs
+ ConcatStrings : String concatenation
+ Configuration : Gets configuration informations
+ Div : Divides its inputs
+ ExecBbiCommand : Executes bbi commands
+ ExecSystemCommand : Executes system (O.S.) commands
+ GetVectorCharElement : Gets the i-th element from the input vector (std...
+ ...
+ MagicBox : Takes *any kind* of data and copies it to its ou...
+ MakeFileName : Makes a kosher file name
+ Mul : Multiplies its inputs
+ MultipleInputs : This box has multiple Void inputs and one Void o...
+ StringRelay : Just copies the value of its input to its output...
+ StringSelect : Outputs the string set to the ith input Ini (In0...
+ user
+ workspace
+\end{verbatim}
+
+Now the interpreter knows the package \texttt{std} and the black boxes it provides,
+such as the \texttt{Add} box, the \texttt{ConcatStrings} box, and so on. Remark that the
+content of \texttt{std} may vary from one version to another
+as new black boxes might be added to it.
+If you type :
+\begin{verbatim}
+> help Add
+\end{verbatim}
+
+You'll get a text help, in the 'Message' part :
+\begin{verbatim}
+Black Box <std::Add>
+ Adds its inputs
+ By : laurent.guigues@creatis.insa-lyon.fr
+ Categories : atomic box;math;
+ * Inputs :
+ 'BoxExecute' <bbtk::Void> [signal] : Any signal received by this input
+ executes the box
+ 'BoxProcessMode' <String> [] : Sets the processing mode of the box
+ (Pipeline | Always | Reactive)
+ 'In1' <Double> [] : First number to add
+ 'In2' <Double> [] : Second number to add
+ * Outputs :
+ 'BoxChange' <bbtk::VoidS> [signal] : Signals modifications of the box
+ 'Out' <Double> [] : Result
+\end{verbatim}
+
+After loading the package it belongs to, you can create an \emph{instance} of an \texttt{Add} box by