dx:todo 

To provide TODO information associated to a parent element or file

Element Information

Model

Attributes

QName Type Fixed Default Use Inheritable Annotation
dx:what xs:string optional
dx:when xs:date optional
dx:who xs:string required

Source 

<xs:element name="todo">
  <xs:annotation>
    <xs:documentation>To provide TODO information associated to a parent element or file</xs:documentation>
  </xs:annotation>
  <xs:complexType>
    <xs:attribute ref="dx:who" use="required"/>
    <xs:attribute ref="dx:when" use="optional"/>
    <xs:attribute ref="dx:what" use="optional"/>
  </xs:complexType>
</xs:element>

Sample