\begin{table}%t1
\caption{\label{tab_review_fit}Root-mean-square (rms) deviations from the global fit$^a$ of
  transitions involving $v_{\rm t} = 0$ torsional energy levels of
  $^{13}$C$_2$-methyl formate (HCOO$^{13}$CH$_3$).} 
%\centerline
 { 
\par
\begin{tabular}{cccccc}
\hline\hline           
\multicolumn{4}{c}{Number of parameters}              & \multicolumn{2}{c}{27}\\
\multicolumn{4}{c}{Number of lines}                   & \multicolumn{2}{c}{936}\\
\multicolumn{4}{c}{rms of the 936 MW $v_{\rm t}=0{-}0$ lines} & \multicolumn{2}{c}{0.0970 MHz}\\
\multicolumn{4}{c}{rms of the 454 A symmetry lines}   & \multicolumn{2}{c}{0.1005 MHz}\\
\multicolumn{4}{c}{rms of the 482 E symmetry lines}   & \multicolumn{2}{c}{0.0937 MHz}\\
\hline
Source$^b$  & Range$^c$ (GHz)  & $J_{\rm max}$, $K_{\rm max}^d$ & Number of
lines$^e$ & Uncertainties$^f$ (MHz) & rms$^g$ (MHz) \\
\hline
Lille FTMW &   4--20      & 7, 3 & 27 & 0.005    & 0.0067 \\
\hline
Lille BWO   & 150--700$^j$ &63, 31&582 & 0.030    & 0.0335 \\
\hline
Lille BWO   & 150--700$^j$ &58, 29& 31 & 0.100$^h$& 0.0705 \\ 
\hline
Oslo Stark &   8--80      &33, 11&223 & 0.150$^i$&        \\
Spectr.    &             &28, 7  & 28 & 0.200$^i$&0.1644  \\
Lille BWO   &150--700$^j$  &58, 34& 45 & 0.200$^h$&        \\
\hline 
\end{tabular}}
\medskip
\par
$^a$ Parameter values are given in Table~\ref{tab_param}.  
The complete list of observed minus calculated residuals of $v_{\rm t} = 0$ lines are given in
Supplementary Table~A.1.    
$^b$ Sources of data:  data come from the present work, the different
instruments are described in Sect.~\ref{subsec-spectr_exp}. 
$^c$ Spectral range of the measurements. 
$^d$ Maximum $J$ and $K_{\rm a}$ for each group of measurements.  
$^e$ Number of MW lines in each uncertainty group. 
$^f$ Uncertainty in MHz used in the fit. 
$^g$ Root mean square deviation in MHz for each group. 
$^h$ The accuracy of spectral measurements for the Lille backwardwave
oscillators spectrometer is about 0.030~MHz for isolated lines but
some lines are either blended or present a bad S/N ratio and
therefore their measurement accuracy is taken as either 0.100~MHz or
0.200~MHz according to the broadening of the experimental line.   
$^i$ The accuracy of spectral measurements for the Oslo Stark
spectrometer is about 0.100~MHz for isolated lines although they are
considered with an experimental error of 0.150~MHz. When the lines are
either blended or present a bad S/N ratio, their measurement accuracy
is taken as 0.200~MHz.  
$^j$ The Lille spectrometer spectral ranges for these measurements
are: 150--245~GHz, 320--350~GHz, 510--525~GHz and 580--661~GHz. 
\end{table}