\begin{definition}[Definition:Inclusion Relation on Subobjects]
Let $\mathbf C$ be a metacategory.
Let $C$ be an object of $\mathbf C$.
Let $\map {\mathbf{Sub}_{\mathbf C} } C$ be the category of subobjects of $C$.
The '''inclusion relation $\subseteq$''' on subobjects of $C$ is defined as follows:
:$m \subseteq m'$ {{iff}} there exists a morphism $f: m \to m'$
\end{definition}