Who is reading, and what they are reading it off.
The declared type, printed as the author wrote it.
What the type needs, phrased to follow "needs" — 'a "map" series', 'a bar or line dataset'.
Optionaldrawn: stringWhat the library actually draws this series as, when the adapter can name it.
Reports a declaration the construct it was written on cannot back — the other half of spec §7.1.
Distinct from warnUndrawnType: the adapter reads this type, but not off this series. A survival curve read off a pie is not a degraded announcement, it is a wrong one, so the reading falls through to the undeclared chart and says which construct the declaration wanted.