yes-no 

The yes-no type is used for boolean-like attributes. We cannot use W3C XML Schema booleans due to their restrictions on expression of boolean values.

Simple Type Information

Used By

Attributes accidental/@cautionary, accidental/@editorial, beam/@repeater, beat-repeat/@use-dots, bend-sound/@accelerate, clef/@additional, degree-alter/@plus-minus, directive/@directive, figured-bass/@parentheses, fingering/@alternate, fingering/@substitution, grace/@slash, harmony/@print-frame, heel-toe/@substitution, key-octave/@cancel, kind/@bracket-degrees, kind/@parentheses-degrees, kind/@stack-degrees, kind/@use-symbols, level-display/@bracket, level-display/@parentheses, level/@reference, measure-attributes/@implicit, measure-attributes/@non-controlling, metronome-tuplet/@bracket, metronome/@parentheses, mordent/@long, multiple-rest/@use-symbols, note/@pizzicato, notehead/@filled, notehead/@parentheses, offset/@sound, pedal/@line, print-attributes/@new-page, print-attributes/@new-system, print-object/@print-object, print-spacing/@print-spacing, printout/@print-dot, printout/@print-lyric, slash/@use-dots, slash/@use-dots, slash/@use-stems, slash/@use-stems, sound/@dacapo, sound/@forward-repeat, sound/@pizzicato, supports/@type, trill-sound/@accelerate, tuplet/@bracket

Source 

<xs:simpleType name="yes-no">
  <xs:annotation>
    <xs:documentation>The yes-no type is used for boolean-like attributes. We cannot use W3C XML Schema booleans due to their restrictions on expression of boolean values.</xs:documentation>
  </xs:annotation>
  <xs:restriction base="xs:token">
    <xs:enumeration value="yes"/>
    <xs:enumeration value="no"/>
  </xs:restriction>
</xs:simpleType>