$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
5.31
\begin{equation} \begin{gathered}\label{equation:cartesian-in-direct-image-3} \xymatrix@R =50pt@C=50pt{ \operatorname{\mathcal{C}}_0 \ar [d] \ar [r]^-{F_0} & \operatorname{\mathcal{D}}\ar [d]^{V} \\ \operatorname{\mathcal{C}}\ar [r]^-{ \overline{F} } \ar@ {-->}[ur]^{F} & \operatorname{\mathcal{E}}. } \end{gathered} \end{equation}