\begin{table}%t5
\caption{\label{steady_state2}Fractional abundances and abundance ratios from the alternative gas-phase model$^a$.}
%\centering
\par
\begin{tabular}{lllllccc}
\hline
\hline\noalign{\smallskip}
 $T = 10$~K  & HNCO/H$_{2}$     & HOCN/H$_2$    & HCNO/H$_2$     & HONC/H$_{2}$      & HNCO/HOCN & HNCO/HCNO  & HCNO/HOCN    \\ 
   &                 $\times 10^{13}$ & $\times 10^{13}$  & $\times 10^{13}$&   $\times 10^{13}$                               &     &    & \\
 \hline\noalign{\smallskip}
 $n$(H$_2$)~cm$^{-3}$ &   &     &      &   &   \\
$1 \times 10^3$     & 3.5 & 0.72 & 4.6 & 1.0 &    4.9    &    0.80     &  6.4  \\
                   & 1000 & 91 & 280 & 170  &     11  &   3.6     & 3.1 \\                  
$3 \times 10^3$   & 9500 & 850 & 630 & 180  &    11   &    15     &  0.7  \\
                    &  21~000 & 1700 & 1200 & 550 &   12    & 17       &  0.7\\
$1 \times 10^4$     & 19~000  & 1500 & 330 & 45 &   13     &    58     & 0.2 \\ 
                   & 48~000 &  2700 &  630 & 120 &  18      &    76       &  0.2 \\
$3 \times  10^4$   & 18~000  & 1300 & 96 & 4.6  &   14     &   190     &  0.07  \\ 
                    &  55~000 & 2100& 190 & 12 &   27    &    300      &   0.09\\
$1 \times  10^5$     & 9400 & 730 & 19 & 0.2  &   13   &   490     &  0.03 \\  
                   & 41~000 & 1100 & 40 & 0.6 &  37     &     1000   &    0.04 \\
$3 \times  10^5$   & 3400 & 330 & 4.4 & 0.02  &   10    &    770   &  0.01 \\ 
                    & 20~000 & 490 &  11 & 0.05 &   40   &   1800 &  0.02 \\
$5 \times 10^5$   & 2000 & 220 & 2.3 & 0.005  &   8.9      &  850   &  0.01 \\ 
                    & 13~000 & 320 & 6.4 & 0.02  &   40    &  2000  &  0.02 \\
10$^6$     & 900 & 120 & 1.0 & 0.001  &    7.3      &    910    &  0.01  \\  
                   & 7100 & 170 & 2.9 & 0.003 &    41    &  2400 &  0.02 \\
\hline
 $T = 50$~K  & HNCO/H$_2$     & HOCN/H$_2$     & HCNO/H$_2$     & HONC/H$_2$      & HNCO/HOCN & HNCO/HCNO  & HCNO/HOCN    \\  
    &                 $\times 10^{13}$ & $\times 10^{13}$  & $\times 10^{13}$&   $\times 10^{13}$                               &     &    & \\
 \hline\noalign{\smallskip}
$n$(H$_2$)~cm$^{-3}$ &   &     &   &   &   &   \\
$1 \times 10^3$     & 17~000  & 590 & 2000 & 1100  &   30     &    8.8     &   3.4   \\  
                      & 26~000 &  930 & 3100 & 2300  &  28      &    8.4  &   3.3  \\
$1\times  10^4$     & 32~000  & 840 & 470 & 66  &  38     &   68  &    0.6 \\ 
                      &  110~000 & 1900 & 970& 110 &  56     &   110      &   0.5\\
$1\times  10^5$     & 9600 & 260 & 26 & 0.4  &  37     &   370       &   0.1 \\  
                     &  49~000 & 720 & 56 & 0.6  &  68       &  880   &  0.08 \\
$1\times  10^6$     & 1000 & 18 & 1.0 & 0.001  &   57     &   990     &   0.06   \\  
                       &  6700 & 25 & 2.3 & 0.002 & 270 &  2900      &  0.09 \\
 \hline
\end{tabular}
\tablefoot{For each density and temperature, the first line refers to steady state whereas the second line 
refers to early time. Early-time results computed at maximum of HNCO abundance.
\tablefoottext{a}{With the rate coefficients for CH$_{2}$ + NO calculated by \citet{zhang04}, in which HCNO is not a major product.  See text.}}
\end{table}