Looking at the following piece, the information says that the key is G minor. However. the score in the "original key" has a key signature of D minor. Moreover, the score transposed to A minor has a key signature of E minor.
I am aware that:
- The music is not strictly in a minor key, but rather in a mode, although I don't see why this would have any effect.
- There are accidentals next to the notes that make the music effectively be in the listed key (so for G minor, the E's are notated with a flat to make it sound G minor, although with a signature of D minor).
I'm not sure if this is bad editing and if when I arrange the piece I can/should use the listed key as the key signature. Or maybe it's some convention that I've yet to see in this type of music.