1-based position within the measure, in time-signature beats (fractional)
Length at the score's own tempo, in milliseconds
Sounding length in quarter notes; tied notes are merged into one
Stable id: <part id>:<index within part>
Another note of the same part starts at the same moment
A grace note: no duration of its own
1-based measure number as written in the file
Sounding pitch as a MIDI note number
Onset at the score's own tempo, in milliseconds
Onset from the start of the score, in quarter notes
OptionalstaffStaff within the part, when the file gives one
MusicXML voice, '1' when the file gives none
Written pitch as a MIDI note number (before transposition)
One sounding note of a score — what the performer is expected to play.