metal lines. The column density of the sub-DLA fitted down to Ly$\beta$ with four components at 0, -55, -95, and -144 km s$^{-1}$, resulting a total of log $N_{{\rm H}\,{\sc \rm I}}=19.96\pm0.09$ and $b=20$, 20, 20 (fixed), and $35\pm3.0$ km s$^{-1}$ respectively. The component at 0 km s$^{-1}$ is strongest and heavily dominates over other components. Strong metal absorption lines from [O]{}[i]{} $\lambda$ 1302, [Fe]{}[ii]{} $\lambda\lambda\lambda\lambda\lambda\lambda\lambda$ 1144, 1608, 1611, 2344, 2374, 2382, 2586, [Si]{}[ii]{} $\lambda\lambda\lambda\lambda\lambda$ 1190, 1193, 1260, 1304, 1526, [C]{}[ii]{} $\lambda$ 1334, [Al]{}[ii]{} $\lambda$ 1670, [Mg]{}[ii]{} $\lambda\lambda$ 2796, 2803, [Al]{}[iii]{} $\lambda\lambda$ 1854, 1862, [Si]{}[iv]{} $\lambda\lambda$ 1393, 1402, and [C]{}[iv]{} $\lambda\lambda$ 1548, 1550 at the redshift of the sub-DLA are covered in the red part of the spectrum. Fig. \[B1036-268\] shows our best fit result of [H]{}[i]{} lines of the sub-DLA.

11. LBQS 1232+0815 ($z_{\rm em}=2.570$). A DLA was known at $z_{\rm abs}=2.338$ along the line-of-sight of this quasar [@prochaska07; @ivanchik10]. We report for the first time a sub-DLA at $z_{\rm abs}=1.720$ with total log $N_{{\rm H}\,{\sc \rm I}}=19.48\pm0.13$. From $\ion{O}{i}$, we identified two main velocity components from the system at 0 and -78 km s$^{-1}$ (see Fig. \[met1232\]) where $b$ is fixed at $b=20$ km s$^{-1}$ for both components. 