Function layout_json 

pub fn layout_json() -> Value

The layout as a value: the version, every table’s slots and width, the codes (kinds, unit and person states, weather, modes, calendars) and the metadata record’s fields. A kind’s code is its index in kinds (the catalog’s order, Kind as usize), and names holds each kind’s catalog name, which is a unit’s label when a full metadata listing leaves the unit out.