Booklet of the source CD set (FARAO Classics B 108 010, in the rip as Scans/booklet.pdf, p.91): "Die Aufnahmen fanden im April 1997 im Muenchner Nationaltheater live statt" / "The recording took place in April 1997 live at the Munich Nationaltheater". Back of box prints (C) 1997; the EAC cue sheets carry REM DATE 1997; Discogs release 28128214 (barcode 4025438080109, the UPC already on this recording) transcribes "Recorded live at the Munich Nationaltheater, April 1997". The stored 2005 was neither a recording nor a release year. Day left unset: only the month is documented. Booklet also notes the production premiered 26 February 1996, which is what the old day/month 1/2 may have come from.

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