The numeral-key type is used when the key for the numeral is different than the key specified by the key signature. The numeral-fifths element specifies the key in the same way as the fifths element. The numeral-mode element specifies the mode similar to the mode element, but with a restricted set of values
The
<numeral-key>element.The numeral-key type is used when the key for the numeral is different than the key specified by the key signature. The numeral-fifths element specifies the key in the same way as the fifths element. The numeral-mode element specifies the mode similar to the mode element, but with a restricted set of values
See
https://www.w3.org/2021/06/musicxml40/musicxml-reference/elements/numeral-key/