  Sr$_2$RuO$_4$ has been under intensive scrutiny over the past years after new
NMR measurements unveiled that the superconducting state might be a spin
singlet. One of the best order parameter candidates in light of these new
experiments is a chiral d-wave state with $d_{xz}+id_{yz}$ symmetry. This order
parameter has been overlooked given the strong two-dimensional character of the
normal state electronic structure. Recently, a phenomenological proposal based
on local interactions with a three-dimensional electronic structure showed that
a chiral d-wave state can be stable in Sr$_2$RuO$_4$ once momentum-dependent
spin-orbit coupling is properly taken into account. Here we discuss the origin
of the nodes and dips in this order parameter as inherited from the normal
state Hamiltonian, showing that a nodal gap can emerge out of purely local
interactions and connect the presence of nodes with the superconducting fitness
measure.
