$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
7.8
\begin{equation} \begin{gathered}\label{equation:cofinal-vs-anodyne} \xymatrix@R =50pt@C=50pt{ A \ar [d]^{f} \ar [r] & X \ar [d]^{q} \\ B \ar@ {-->}[ur] \ar [r]^-{g} & S } \end{gathered} \end{equation}