  Several possible odd-parity states are listed up group-theoretically and
examined in light of recent experiments on Sr$_2$RuO$_4$. Those include some of
the $f$-wave pairing states, ${\mib d}({\mib k})\propto{\hat{\mib z}}
k_xk_y(k_x + {\rm i}k_y)$ and ${\hat{\mib z}} (k_x^2-k_y^2)(k_x + {\rm i}k_y)$
and other ${\hat{\mib z}} (k_x + {\rm i}k_y)\cos ck_z$ ($c$ is the $c$-axis
lattice constant) as most plausible candidates. These are time-reversal
symmetry broken states and have line nodes running either vertically (the
former two) or horizontally (the latter), consistent with experiments.
Characterizations of these states and other possibilities are given.
