<xs:element name="key-step" type="step">
  <xs:annotation>
    <xs:documentation>Non-traditional key signatures can be represented using the Humdrum/Scot concept of a list of altered tones. The key-step element indicates the pitch step to be altered, represented using the same names as in the step element.</xs:documentation>
  </xs:annotation>
</xs:element>

<xs:element name="key-alter" type="semitones">
  <xs:annotation>
    <xs:documentation>Non-traditional key signatures can be represented using the Humdrum/Scot concept of a list of altered tones. The key-alter element represents the alteration for a given pitch step, represented with semitones in the same manner as the alter element.</xs:documentation>
  </xs:annotation>
</xs:element>

<xs:group name="non-traditional-key">
  <xs:annotation>
    <xs:documentation>The non-traditional-key group represents a single alteration within a non-traditional key signature. A sequence of these groups makes up a non-traditional key signature</xs:documentation>
  </xs:annotation>
  <xs:sequence>
    <xs:element name="key-step" type="step">
      <xs:annotation>
        <xs:documentation>Non-traditional key signatures can be represented using the Humdrum/Scot concept of a list of altered tones. The key-step element indicates the pitch step to be altered, represented using the same names as in the step element.</xs:documentation>
      </xs:annotation>
    </xs:element>
    <xs:element name="key-alter" type="semitones">
      <xs:annotation>
        <xs:documentation>Non-traditional key signatures can be represented using the Humdrum/Scot concept of a list of altered tones. The key-alter element represents the alteration for a given pitch step, represented with semitones in the same manner as the alter element.</xs:documentation>
      </xs:annotation>
    </xs:element>
  </xs:sequence>
</xs:group>