Here $ \Property\ h $ gives the appropriate access relation according to
the $ h $ flag (this is the primitive function that inspects the {\RDF}
-graph, see \subsecref{HighAccess}).
-
+graph).
+
$ \Src\ k\ P\ V $ is a helper function giving the source set
according to the $ k $ flag. $ \Src $ is based on $ \Match $, the helper
function handling {\POSIX} regular expressions.
\GP{query} $ is the primitive function performing the low level invocation.
The core language does not include any external function of this kind and it
is a mistake to invoke an undefined function.
-The construction ``\TT{gen} p \TT{in} x'' rewrites to ``\TT{gen} p \{x\}''.
+The construction ``\TT{gen} p \TT{in} x'' rewrites to ``\TT{gen} p \verb+{+x\verb+}+''.
\end{itemize}