Function point_renames 

pub fn point_renames(base: &Value, after: &Value) -> PointRenames

Which point of one part document became which in another, per group, and on what evidence. There is no id behind a point any more, so this is how a consumer that must carry something across a part refresh — an eCAD sheet’s terminals, for one — learns that VCC became VDD rather than being deleted and replaced.

Two passes. The ANCHOR pass pairs points that both versions seat the same way; that pairing is evidence, not a guess, and it is what makes a rename survive across two SAVED versions of a part. Whatever it does not pair falls to the POSITIONAL pass, which reads the remaining names the same way a follow call reads one edit’s worth of them — and which cannot tell a rename from a delete-and-add. The two are kept apart so the consumer can say which it acted on.