\section{RPID Elements}
\label{sec:elements}

\subsection{Introduction}

Below, we describe the RPID elements in detail.  
\xmlelement{activity}, 
\xmlelement{idle} 
\xmlelement{placetype},
\xmlelement{privacy},
\xmlelement{relationship}, 
extend the PIDF \xmlelement{status} element, while
\xmlelement{class} and
\xmlelement{contacttype} extend the PIDF \xmlelement{tuple} element.

In general, it is highly unlikely that a presentity will publish or
announce all of these elements at the same time.  Rather, these elements
were chosen to give the presentity maximum flexibility in deriving this
information from existing sources, such as calendaring tools, device
activity sensors or location trackers, as well as to manually configure
this information.

The namespace URIs for these elements defined by this specification are URNs
\citenorm{rfc2141}, using the namespace identifier 'ietf' defined by
\citenorm{rfc2648} and extended by
\citenorm{draft-mealling-iana-xmlns-registry}:

\begin{verbatim}
   urn:ietf:params:xml:ns:pidf:rpid-status
   urn:ietf:params:xml:ns:pidf:rpid-tuple
\end{verbatim}
