Optional ReadonlylastThe last good (non-null) value seen from the timed-out source and its original timestamp. Absent if no good value was ever received.
Optional ReadonlytimedSet to true on the synthetic delta the server emits when a source's
meta.timeout has elapsed since its last update. A sensor that
legitimately publishes value: null (e.g. an echosounder with no
bottom return) does not carry this flag.
Out-of-band metadata about a particular delta value, set by the server when a value is anything other than a fresh reading from its source. Distinct from
Meta(which describes the path itself) and fromvalue(which is what the source reported). Clients that don't recognisestateignore it.