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. last_name: "Schäfer" -> "Schäfer"

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 "Schäfer" is being corrected to "Schäfer". 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.