  Magnetic field relaxation is determined by both the field's geometry and its
topology. For relaxation processes, however, it turns out that its topology is
a much more stringent constraint. As quantifier for the topology we use
magnetic helicity and test whether it is a stronger condition than the linking
of field lines. Further, we search for evidence of other topological
invariants, which give rise to further restrictions in the field's relaxation.
We find that magnetic helicity is the sole determinant in most cases.
Nevertheless, we see evidence for restrictions not captured through magnetic
helicity.
