$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
8.11
\begin{equation} \begin{gathered}\label{equation:relative-outer-horn-filling3} \xymatrix@R =50pt@C=50pt{ \Lambda ^{d}_{d'} \ar [r]^-{ \rho _0 } \ar [d] & \operatorname{\mathcal{C}}\ar [d]^{U} \\ \Delta ^{d} \ar@ {-->}[ur] \ar [r]^-{ \overline{F} \circ \tau _{\ell } } & \operatorname{\mathcal{D}}} \end{gathered} \end{equation}