source: https://www.w3.org/2021/06/musicxml40/musicxml-reference/elements/alter/
MusicXML 4.0 >
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alter
Parent element:
<pitch>
The element represents chromatic alteration in number of semitones (e.g., -1 for flat, 1 for sharp). Decimal values like 0.5 (quarter tone sharp) are used for microtones.
semitones
None.
This element is used in the following examples:
, (Microtones), (Semitones), , , (Multiple Stop), , , , , , , , (Symbols), , , , Tutorial: Après un rêve, Tutorial: Chopin Prelude, Tutorial: Tablature