\begin{table}%t15
%\centering
\par
\caption{Observed and model line ratios; $3.5 \leq z < 4.0$.\label{table:15a}}
\begin{tabular}{l c c c c}
\hline\hline
  Parameter                                &
  Obs.                                     &
  Err.$^{{a}}$                      &
  \multicolumn{2}{c}{Models$^{{b}}$}\\
\hline
\multicolumn{5}{c}{$-25.5  >  M_B  \geq  -26.5$} \\
\hline
  $Z/Z_\odot$                       &       &       &   5.0 &   2.0 \\
  $\beta$                           &       &       &--1.00 &--1.13 \\
  $\Gamma$                          &       &       &--1.00 &--1.60 \\
  N{\sc v}/C{\sc iv}                & 0.618 & 0.031 & 0.499 & 0.406 \\
  (O{\sc i}+Si{\sc ii})/C{\sc iv}   & 0.098 & 0.010 & 0.163 & 0.045 \\
  C{\sc ii}/C{\sc iv}               & 0.030 & 0.010 & 0.199 & 0.091 \\
  (Si{\sc iv}+O{\sc iv}])/C{\sc iv} & 0.261 & 0.013 & 0.322 & 0.255 \\
  N{\sc iv}]/C{\sc iv}              & 0.038 & 0.010 & 0.152 & 0.064 \\
  He{\sc ii}/C{\sc iv}              & 0.153 & 0.010 & 0.186 & 0.202 \\
  (O{\sc iii}]+Al{\sc ii})/C{\sc iv}& 0.097 & 0.010 & 0.289 & 0.175 \\
  Al{\sc iii}/C{\sc iv}             & 0.084 & 0.010 & 0.101 & 0.049 \\
  Si{\sc iii}]/C{\sc iv}            & 0.066 & 0.010 & 0.266 & 0.090 \\
  C{\sc iii}]/C{\sc iv}             & 0.355 & 0.018 & 0.474 & 0.243 \\
\hline
\multicolumn{5}{c}{$-26.5   >   M_B   \geq   -27.5$} \\
\hline
  $Z/Z_\odot$                       &       &       &   5.0 &   5.0 \\
  $\beta$                           &       &       &--1.00 &--1.08 \\
  $\Gamma$                          &       &       &--1.00 &--1.54 \\
  N{\sc v}/C{\sc iv}                & 0.856 & 0.043 & 0.499 & 0.796 \\
  (O{\sc i}+Si{\sc ii})/C{\sc iv}   & 0.105 & 0.010 & 0.163 & 0.086 \\
  C{\sc ii}/C{\sc iv}               & 0.051 & 0.010 & 0.199 & 0.186 \\
  (Si{\sc iv}+O{\sc iv}])/C{\sc iv} & 0.347 & 0.017 & 0.322 & 0.415 \\
  N{\sc iv}]/C{\sc iv}              & 0.025 & 0.010 & 0.152 & 0.148 \\
  He{\sc ii}/C{\sc iv}              & 0.145 & 0.010 & 0.186 & 0.198 \\
  (O{\sc iii}]+Al{\sc ii})/C{\sc iv}& 0.101 & 0.010 & 0.289 & 0.274 \\
  Al{\sc iii}/C{\sc iv}             & 0.098 & 0.010 & 0.101 & 0.101 \\
  Si{\sc iii}]/C{\sc iv}            & 0.122 & 0.010 & 0.266 & 0.158 \\
  C{\sc iii}]/C{\sc iv}             & 0.332 & 0.017 & 0.474 & 0.323 \\
\hline
\multicolumn{5}{c}{$-27.5 >  M_B  \geq  -28.5$} \\
\hline
  $Z/Z_\odot$                       &       &       &   5.0 &   5.0 \\
  $\beta$                           &       &       &--1.00 &--1.07 \\
  $\Gamma$                          &       &       &--1.00 &--1.50 \\
  N{\sc v}/C{\sc iv}                & 1.062 & 0.053 & 0.499 & 0.773 \\
  (O{\sc i}+Si{\sc ii})/C{\sc iv}   & 0.115 & 0.010 & 0.163 & 0.089 \\
  C{\sc ii}/C{\sc iv}               & 0.062 & 0.010 & 0.199 & 0.187 \\
  (Si{\sc iv}+O{\sc iv}])/C{\sc iv} & 0.395 & 0.020 & 0.322 & 0.410 \\
  N{\sc iv}]/C{\sc iv}              & 0.016 & 0.010 & 0.152 & 0.147 \\
  He{\sc ii}/C{\sc iv}              & 0.128 & 0.010 & 0.186 & 0.197 \\
  (O{\sc iii}]+Al{\sc ii})/C{\sc iv}& 0.089 & 0.010 & 0.289 & 0.274 \\
  Al{\sc iii}/C{\sc iv}             & 0.122 & 0.010 & 0.101 & 0.102 \\
  Si{\sc iii}]/C{\sc iv}            & 0.186 & 0.010 & 0.266 & 0.164 \\
  C{\sc iii}]/C{\sc iv}             & 0.343 & 0.017 & 0.474 & 0.329 \\
\hline
\multicolumn{5}{c}{$-28.5   >   M_B  \geq   -29.5$} \\
\hline
  $Z/Z_\odot$                       &       &       &   5.0 &   5.0 \\
  $\beta$                           &       &       &--1.00 &--1.02 \\
  $\Gamma$                          &       &       &--1.00 &--1.28 \\
  N{\sc v}/C{\sc iv}                & 1.006 & 0.050 & 0.499 & 0.639 \\ 
  (O{\sc i}+Si{\sc ii})/C{\sc iv}   & 0.180 & 0.010 & 0.163 & 0.118 \\
  C{\sc ii}/C{\sc iv}               & 0.105 & 0.010 & 0.199 & 0.194 \\
  (Si{\sc iv}+O{\sc iv}])/C{\sc iv} & 0.421 & 0.021 & 0.322 & 0.377 \\
  N{\sc iv}]/C{\sc iv}              & 0.031 & 0.010 & 0.152 & 0.143 \\
  He{\sc ii}/C{\sc iv}              & 0.108 & 0.010 & 0.186 & 0.194 \\
  (O{\sc iii}]+Al{\sc ii})/C{\sc iv}& 0.056 & 0.010 & 0.289 & 0.276 \\
  Al{\sc iii}/C{\sc iv}             & 0.124 & 0.010 & 0.101 & 0.107 \\
  Si{\sc iii}]/C{\sc iv}            & 0.193 & 0.010 & 0.266 & 0.203 \\
  C{\sc iii}]/C{\sc iv}             & 0.426 & 0.021 & 0.474 & 0.369 \\
\hline
\end{tabular}
\par
\smallskip
$^{{a}}$
   Errors adopted for carrying out model fittings.
   Values are changed from those presented in
   Table 6; see text for details.\\
$^{{b}}$
   Model predictions with fixed $\beta$ and~$\Gamma$
   and those with varying $\beta$ and~$\Gamma$ are
   given in the left and right columns, respectively.
\end{table}