Reification styles have two boolean components: whether the
graph+reifier will intercept reification triples or not [if not, the only
in-Jena reification is through the reifyAs operation], and whether or
not reification triples will be visible in the graph.
Answer a human-readable representation of this reification style. If it's
one of the three standard constants, return their names; otherwise return
a description of the fields. code should not rely on these values;
they may be changed for debugging or convenience.