$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$
7.92
\begin{equation} \begin{gathered}\label{equation:cartesian-transformation-in-spaces2} \xymatrix { \mathscr {F}(C) \ar [d]^{\mathscr {F}(u) } \ar [r]^{ \gamma _{C} } & \mathscr {F}'(C) \ar [d]^{ \mathscr {F}'(u) } \\ \mathscr {F}(D) \ar [r]^{\gamma _{D}} & \mathscr {F}'(D) } \end{gathered} \end{equation}