If
the base object shape you selected is influenced by only one blend
shape deformer, you don’t need to set Specify Node on.
If on, you can specify BlendShape Node and Existing Nodes.
Default is off.
BlendShape Node
Specifies the
name of the blend shape deformer whose target object shapes you
want to remove. (Available if Specify Node is on.)
Existing Nodes
Lists
all the blend shape deformer nodes in the scene, and indicates the
blend shape deformer whose target object shapes you want to remove.
Only available if Specify Node is on.