Wounds on moving character \ pre-skinned local position

Hi there!
Can someone explain me how to use “pre-skinned local position”?

i want to render wounds on moving character
something similar to Tom Looman article

"There is a way to optimize the technique, by using the fairly recently added pre-skinned local position node. This replaces the world position we bake into the render target with the pre-skinned local position. By doing this, we only require a capture once which we can do offline (since this position never changes at runtime). To capture the reference pose locations I made a quick blueprint and modified version of Ryan’s unwrap material, captured the scene and turned the RT into a static texture (You can see an animated version of what this looks like below). This eliminates the need for the second render target at run-time entirely. Each hit, we transform the hit location (world-space) into the pre-skinned local-space of the mesh before we can apply it to the character. In the next section I’ll explain more how the transforming from world space to pre-skinned space works.