ice-offer-group

<xs:element name="ice-offer-group">
  <xs:complexType>
    <xs:choice>
      <xs:element ref="ice-offer-group" maxOccurs="unbounded"/>
      <xs:element ref="ice-offer" maxOccurs="unbounded"/>
    </xs:choice>
    <xs:attribute name="description" use="required"/>
  </xs:complexType>
</xs:element>