The docs page at https://docs.mongodb.com/manual/reference/bson-types/ still listed type 14 (Symbol), but it has been deprecated since 2011 (https://github.com/mongodb/bsonspec.org/commit/b5b60d6eca910a139a91736922cc04dc30ccdb34) and also listed as deprecated in the bsonspec page (http://bsonspec.org/spec.html)