harmonic frequencies in swept pss

In case of swept PSS , the harmonicFreqList seems to have only the 2
extreme (min & max) frequencies corresponding to min/max values of the
sweep variable, for each harmonic -

harmonicFreqList( ?result "pss_fd")
((0 0.0)
(1 (3.646369e+08 1.168354e+09)
)
(2
(7.292738e+08 2.336708e+09)
)
..
..
How do I get frequencies corresponding to the intermediate sweep
values ?

Thanks...