Optional__kindDiscriminator kind, written on serialization (SohlEntity.toJSON) and read back on revival. Optional as constructor input — it is derived from the concrete class, not supplied by callers.
Persisted hit locations, in order; each names its part by shortcode.
Persisted body parts, in order; each names its zone by shortcode.
Persisted body zones, in order; their order sets zone-number runs.
Persisted data shape for a complete body structure — three flat arrays, assembled into a hierarchy by the BodyStructure constructor.