Online help can be provided on different ways:
\begin{itemize}
\item \textsc{pdf} annotations\\
Annotations are represented using icons. If the user moves the mouse
over an annotation icon, the annotation text is shown in a tooltip. If the
user double-clicks the annotation, the note is shown on the screen.\\
Advantage: Annotations do not need JavaScript.\\
Disadvantage: Place is needed for the icons.
\item tooltips\\
Tooltip text is shown if the user moves the mouse over a form field.
Most users know the concept of tooltips from other applications.\\
Tooltip text can not (yet?\footnote{2008-02-07}) be set using
hyperrefs form field options, so we use JavaScript instructions
to set up tooltips.
\end{itemize}