number-level data type
Slurs, tuplets, and many other features can be concurrent and overlap within a single musical part. The number-level entity distinguishes up to 16 concurrent objects of the same type when the objects overlap in MusicXML document order. Values greater than 6 are usually only needed for music with a large number of divisi staves in a single part, or if there are more than 6 cross-staff arpeggios in a single measure. When a number-level value is optional and has no default value, it is 1 if not specified.
When polyphonic parts are involved, the ordering within a MusicXML document can differ from musical score order. As an example, say we have a piano part in 4/4 where within a single measure, all the notes on the top staff are followed by all the notes on the bottom staff. In this example, each staff has a slur that starts on beat 2 and stops on beat 3, and there is a third slur that goes from beat 1 of one staff to beat 4 of the other staff.
In this situation, the two mid-measure slurs can use the same number because they do not overlap in MusicXML document order, even though they do overlap in musical score order. Within the MusicXML document, the top staff slur will both start and stop before the bottom staff slur starts and stops.
If the cross-staff slur starts in the top staff and stops in the bottom staff, it will need a separate number from the mid-measure slurs because it overlaps those slurs in MusicXML document order. However, if the cross-staff slur starts in the bottom staff and stops in the top staff, all three slurs can use the same number. None of them overlap within the MusicXML document, even though they all overlap each other in the musical score order. Within the MusicXML document, the start and stop of the top-staff slur will be followed by the stop and start of the cross-staff slur, followed by the start and stop of the bottom-staff slur.
As this example demonstrates, a reading program should be prepared to handle cases where the number-levels start and stop in an arbitrary order. Because the start and stop values refer to musical score order, a program may find the stopping point of an object earlier in the MusicXML document than it will find its starting point.
Base type: positiveInteger
Minimum allowed value: 1
Maximum allowed value: 16
Where is this type used?
<arpeggiate> — "number" attribute
<bracket> — "number" attribute
<dashes> — "number" attribute
<glissando> — "number" attribute
<hammer-on> — "number" attribute
<non-arpeggiate> — "number" attribute
<octave-shift> — "number" attribute
<other-notation> — "number" attribute
<pedal> — "number" attribute
<pull-off> — "number" attribute
<slide> — "number" attribute
<slur> — "number" attribute
<tied> — "number" attribute
<tuplet> — "number" attribute
<wavy-line> — "number" attribute
<wedge> — "number" attribute