set_isolation的选项-source 和-sink如何理解啊？

我看manpage上写的是如下描述，意思是这样的吗?
如果一条跨PD的net，PD1中的driver cell的supply set是SS1，PD2中的load cell的supply set是SS2，那么我用set_isolation -source SS1 -sink SS2, 就可以插入一个isolation，至于这个isolation的方向，到底是isolation哪个PD的关断影响，这个是tool自己考虑power state table的，不需要参数设定?
o The -source option specifies a supply set name. The isolationstrat-
egyappliesonlytothe domain-crossing nets that are driven by a
cell powered by the specified supply set.
o The -sink option specifies a supply set name. The isolationstrategy
appliesonlyto the domain-crossing nets that fan out to cells pow-
ered by the specified supply set.
You can use both the -source and -sink options to restrict the inser-
tionofisolationcellsto only the domain-crossing nets that are
driven by a cell powered by a specified supply set and thatfanout
to cells powered by a different specified supply set.
oThe -diff_supply_only option, when set to true, applies the strategy
only to the domain-crossing nets in which thedriverandreceivers
arepoweredbydifferentsupply sets or supply nets. This setting
prevents isolation when the driver and receivercellsusematching
supplies.Thedefault is false, meaning no restriction on isolation
based on matching driver and receiver supplies.

有人知道是这样子的吗?