  We give some constraints on intersection forms of spin 4-manifolds bounded by
Seifert rational homology 3-spheres in terms of the $\bar{\mu}$ invariant and
compare them with those in terms of the $\kappa$ invariant. We also show that
the difference between $\kappa$ and $-\bar{\mu}$ for a Seifert rational
homology 3-sphere is at most 2, and under certain extra conditions the
difference is 0.
