unstress 

The unstress element indicates an unstressed note. It is often notated using a u-shaped symbol.

Element Information

Model

Attributes

QName Type Fixed Default Use Inheritable Annotation
color color optional
default-x tenths optional
default-y tenths optional
font-family comma-separated-text optional
font-size font-size optional
font-style font-style optional
font-weight font-weight optional
placement above-below optional
relative-x tenths optional
relative-y tenths optional

Source 

<xs:element name="unstress" type="empty-placement">
  <xs:annotation>
    <xs:documentation>The unstress element indicates an unstressed note. It is often notated using a u-shaped symbol.</xs:documentation>
  </xs:annotation>
</xs:element>

Sample