\begin{document}

\ontology#testOntology
	\struct#test[root=true]
		\field
			\childRef[ref=a]
	\struct#a[transparent=true]
		\primitive[type=string]
	\annotation#comment
		\primitive[type=string]

\begin{test}
This is a <\comment{Not a nice test!}test\> for annotations.
\end{test}

\end{document}