I see some tables with a horizontal line placed at the middle of a cell, for terms not available or not applicable. For example, how shall I replace the "N.A." below with such a line?
\begin{table}[htbp]
\centering
\caption{Caption}
\begin{tabular}{ccc}
\hline
Auctions of & P\_value & $\widehat{\theta}$ \\
\midrule
2 & 0.375 & $\underset{(0.230)}{0.354}$ \\
3 & 0.002 & N.A. \\
\bottomrule
\end{tabular}
\end{table}
I suggest defining a command \NA that holds an em-dash ---:
\documentclass{article}
\usepackage{booktabs,amsmath}
\newcommand{\NA}{---}
\begin{document}
\begin{tabular}{ccc}
\toprule
Auctions of & \detokenize{P_value} & $\widehat{\theta}$ \\
\midrule
2 & 0.375 & $\underset{(0.230)}{0.354}$ \\
3 & 0.002 & \NA \\
\bottomrule
\end{tabular}
\end{document}
This way, if you don't like it later (in life), just change the definition to something more suitable (perhaps an en-dash --).
\---enough? Or maybe\--or even\verb+-+. – Sigur May 16 '14 at 23:33\---and\--? Did you mean---and--? – egreg May 17 '14 at 08:09\-gives a discretionary hyphen, so\---is a discretionary hyphen followed by an en-dash. – egreg May 17 '14 at 16:56---and\---? – Sigur May 17 '14 at 17:02\-is a control symbol, so it's already a complete control sequence name;\---is three tokens:\-,-and-; unless you change the definition of\-,\-is a discretionary hyphen and, at typesetting time,--is converted to an en-dash. – egreg May 17 '14 at 17:06foo-foo\-foo--foo---foofoo-foo\-foo\--foo---foofoo-foo\-foo\--foo\---foo– Sigur May 17 '14 at 17:15---. – Sigur May 17 '14 at 18:13