Paragraphs must be separated by a blank line.

\section{Section heading}
\label{sec:some_name}

\subsection{Subsection}
\label{sec:uac} for example

\subsubsection{Sub-subsection}
\label{sec:register}

References to labels, e.g.,: 

"Section~\ref{sec:uac} describes UACs, while Table~\ref{tab:methods}
shows methods."

Note the ~ (prevents splitting across lines)


bulletted list:

\begin{itemize}
\item first item
\item second item
\end{itemize}

description list

\begin{description}
\item[Label1:] some explanation
\item[Label2:] more explanation
\end{description}


{\SHOULD}, {\MUST}, etc.

{\INVITE}, {\REGISTER}, etc.

\header{To}, \header{From}, anything that is a syntax element
(parameters, etc.) is included in \header{} and writte as

  ... the \header{Foobar} header field ...


\begin{table}[htbp]
\begin{tabular}{lll}
value1 & value2 & value3\\
line2 & line2 more & \\
\end{tabular}
\caption{This is a table caption}
\label{tab:somename}
\end{table}

Note on terminology: it's header fields, not headers.

Note: timer values should be in $$, e.g., $T1$ and $T2$.

All RFC references should have the following form:

"The searching technique outlined in RFC 2052 \cite{rfc2052} ..."

http://www.cs.columbia.edu/sip/draft/base/ has the semi-current version of
bis-04, as a source of examples.

"a 2xx-class response" or "a 2xx response"