by the shell (single quotes).
<citerefentry project='man-pages'><refentrytitle>echo</refentrytitle><manvolnum>1</manvolnum></citerefentry>
is called with [<literal>/usr/bin/echo</literal>,
- <literal>[]</literal>, <literal>[${INVOCATION_ID}]</literal>] as the argument array, and then
+ <literal><></literal>, <literal><${INVOCATION_ID}></literal>] as the argument array, and then
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
generates <varname>${INVOCATION_ID}</varname> and substitutes it in the command-line. This substitution
could not be done on the client side, because the target ID that will be set for the service isn't