pub type Extra = BTreeMap<String, Value>;Expand description
Fields this build doesn’t know about, carried through untouched.
A browser may ignore what it doesn’t understand — it throws its parse away. A tool may not: it reads a world, changes one thing and writes it back, and anything it silently dropped is deleted from the author’s disk. That includes every field added by an emitter newer than the reader, which is most of them over a format’s life. So the structs keep the strangers.
Aliased Type§
pub struct Extra { /* private fields */ }