1. plot the top level nodes
. option POSTLVL= N
(N= 1--> top level, N=2--> only the second level)
or
.option POSTTOP
2. the POSTTOP and POSTLVL options will be ignored if
.option PROBE
is also in the netlist.
[Ref] http://www.designers-guide.org/Forum/YaBB.pl?num=1241031816
