$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
8.5
\begin{equation} \begin{gathered}\label{equation:cospan-Kan-fibration} \xymatrix@R =50pt@C=50pt{ A \ar [r] \ar [d]^{i} & \operatorname{Cospan}(\operatorname{\mathcal{C}}) \ar [d]^{ \operatorname{Cospan}(U) } \\ B \ar [r] \ar@ {-->}[ur] & \operatorname{Cospan}(\operatorname{\mathcal{D}}) } \end{gathered} \end{equation}