The returned value is a vertex number that can be used with the Set Attribute VOP to change the value of the vertex, but is not the final vertex number of the vertex.
This only works in certain VOP contexts where geometry creation is enabled. In particular, the Geometry VOP DOP, Geometry Wrangle DOP, POP VOP DOP, POP Wrangle DOP, Attrib VOP SOP, Attrib Wrangle SOP, Volume VOP SOP, Volume Wrangle SOP.
All geometry creation is done after all the elements have been processed. Therefore, you cannot read from geometry you just created.
Refers to what geometry to write to. The default of 0 means the currently processed geometry.
Which primitive to append a vertex to.
Which point to wire into the newly created vertex.