$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
4.36
\begin{equation} \begin{gathered}\label{diagram:categorical-pushout-square1} \xymatrix@R =50pt@C=50pt{ A \ar [r]^-{f} \ar [d] & A_0 \ar [d] \\ A_1 \ar [r] & A_{01}, } \end{gathered} \end{equation}