Migration: a zero year, month, day or OperaClass id meant the value was unknown, not that it was zero. Set to null.

Repairing UTF-8 that had been stored as Latin-1. The correction is mechanical, not a guess: the stored text re-encodes to exactly these bytes. first_name: "María Carmen Campos" -> "María Carmen Campos"

Repairing character-encoding corruption (mojibake) introduced during data import; the person/ensemble name itself is unchanged. Cause: UTF-8 bytes were decoded as Windows-1252 at import, so each non-ASCII letter became a 2-character sequence. Stored value "María Carmen Campos" is being corrected to "María Carmen Campos". Detected by decoding the stored text back through the offending codec and confirming it yields valid UTF-8. Part of a sweep of all singers, conductors, composers, characters, operas and recordings; 419 fields matched.