# Referencing items while using uncover

I am writing a presentation (using beamer) for a seminar and I just faced a problem I can't handle.

On one slide, I have a big equation and then use an uncover-list to explain all the elements in detail. Later on, I want to have a reference to one particular explanation so that I can click it and go back to the equation, with the explanation highlighted.

However, the reference points to the beginning of the slide (i.e. equation shown, items semi-transparent). But I want to go to the specific slide - the one with a specific item of the itemize highlighted.

Below is a minimal example of the problem I have encountered. How do I cope with it?

\begin{frame}
% big nasty equation here
\begin{itemize}
% explanations for parts of the equation here
\setbeamercovered{transparent}
\uncover<2>{
\item first item
}
\uncover<3>{
\item second item
}
\uncover<4>{
\item third item
}
\uncover<5>{
\item \label{special_item} fourth item
}
\end{itemize}
\end{frame}
% skipping some frames here
\begin{frame}
\ref{special_item}
\end{frame}

-

This is described in Section 11 of the beamer user guide:

\documentclass{beamer}

\begin{document}
\begin{frame}
% big nasty equation here
\begin{itemize}
% explanations for parts of the equation here
\setbeamercovered{transparent}
\uncover<2>{
\item first item
}
\uncover<3>{
\item second item
}
\uncover<4>{
\item third item
}
\uncover<5>{
\hypertarget<5>{special_item}{}
\item fourth item
}
\end{itemize}

\end{frame}
% skipping some frames here
\begin{frame}
\ref{special_item}
\end{frame}
\end{document}

-
For some reason, \ref{special_item} complains about the reference being undefined. However, the \hyperlink{}{} works. I prefer this solution to the one presented by percusse, because the declaration of the 'sub-slide' the link has to point to is closer to the slide itself, making it easier to maintain. Oh, an thank you for pointing to the doc. I guess you're entitled to say RTFM now :) –  dare2be Dec 20 '11 at 9:46

It's better to refer to the frames/slides rather than items. Also you can feed the labels as options to the frame environment.

\documentclass{beamer}
\begin{document}
\begin{frame}[label=eqframe]
$(Big)^{nasty}\sum quation= Here$
\begin{itemize}
% explanations for parts of the equation here
\setbeamercovered{transparent}
\uncover<2>{
\item first item
}
\uncover<3>{
\item second item
}
\uncover<4>{
\item third item
}
\uncover<5>{
\item fourth item
}
\end{itemize}
\end{frame}
% skipping some frames here
\begin{frame}