$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
8.25
\begin{equation} \begin{gathered}\label{equation:dual-Beck-Chevalley-nonsense} \xymatrix@R =50pt@C=50pt{ X \ar [r]^-{g'} \ar [d]^{f} & X_0 \ar [d]^{f'} \\ X_1 \ar [r]^-{g} & X_{01} } \end{gathered} \end{equation}