$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
9.38
\begin{equation} \begin{gathered}\label{equation:describe-relative-cocompletion2} \xymatrix@R =50pt@C=50pt{ \operatorname{\mathcal{E}}\ar [rr]^-{H} \ar [dr]_{U} & & \widehat{\operatorname{\mathcal{E}}} \ar [dl]^{\widehat{U}} \\ & \operatorname{\mathcal{C}}. & } \end{gathered} \end{equation}