\section{Initial Namespace Registrations}
\label{sec:namespace}

\subsection{Namespace dsn}

This document defines the namespace ``dsn''.  The namespace ``dsn''
(Defense Switched Network), contains the priority values
``flash-override'', ``flash'', ``immediate'', ``priority'', ``routine'',
with ``flash-override'' as the highest priority value and ``routine'' as
the lowest.

The values are adopted from RFC 791 \citenorm{rfc791}, omitting the
levels ``critic-ecp'', ``network control'' and ``internetwork control'',
as these are inappropriate here.

\subsection{Namespace q735}

This document also defines the namespace ``q735''.  The namespace
``q735'' supports interworking with Q.735.3 (or equivalent) GSTN (ISDN)
entities; this allows, for example, carrying information between Q.735.3
entities without loss of information.  One or both of the SIP endpoints
might be PSTN gateways.  The namespace contains the priority values
``0'', ``1'', ``2'', ``3'' and ``4'', with ``4'' representing the lowest
priority and ``0'' the highest.

\subsection{Namespace DRSN} 

This document defines the namespace ``drsn''.  The namespace ``drsn''
(Defense Red Switched Network) contains the priority values
``flash-override-override'', ``flash-override'', ``flash'',
``immediate'', ``priority'', ``routine'', with
``flash-override-override'' as the highest priority value and
``routine'' as the lowest.
