doubledAbove property
MusicXML 4.0 <double above="yes"/>: the doubling is an octave UP.
The above attribute is optional and defaults to no, so a bare
<double/> means an octave DOWN — which is why this defaults to false
and why semitones subtracts 12 in that case. Before 2.7.1 the model had
no way to express above="yes" at all: a part declaring it sounded 12
semitones LOW instead of 12 high, a measured 24-semitone (two-octave)
error.
Ignored when doubled is false.
Implementation
final bool doubledAbove;