<xs:element name="group" maxOccurs="unbounded">
    <xs:annotation>
        <xs:documentation>A mixed set of group references and references to items or Web resources</xs:documentation>
    </xs:annotation>
    <xs:complexType>
        <xs:choice minOccurs="0" maxOccurs="unbounded">
            <xs:element name="groupRef">
                <xs:annotation>
                    <xs:documentation>A reference to a group local to the package</xs:documentation>
                </xs:annotation>
                <xs:complexType>
                    <xs:attribute name="idref" type="xs:IDREF" use="required">
                        <xs:annotation>
                            <xs:documentation>The reference to the id of a local group</xs:documentation>
                        </xs:annotation>
                    </xs:attribute>
                    <xs:anyAttribute namespace="##other" processContents="lax" />
                </xs:complexType>
            </xs:element>
            <xs:element name="itemRef" type="LinkType">
                <xs:annotation>
                    <xs:documentation>A reference to a target item or Web resource</xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="conceptRef">
                <xs:annotation>
                    <xs:documentation>A reference to a target concept
</xs:documentation>
                </xs:annotation>
                <xs:complexType>
                    <xs:complexContent>
                        <xs:extension base="FlexPropType" />
                    </xs:complexContent>
                </xs:complexType>
            </xs:element>
        </xs:choice>
        <xs:attribute name="id" type="xs:ID" use="required">
            <xs:annotation>
                <xs:documentation>The local identifier of the group</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="role" type="QCodeType" use="required">
            <xs:annotation>
                <xs:documentation>The part this group plays within its container</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="mode" type="QCodeType">
            <xs:annotation>
                <xs:documentation>An indication whether the elements in the group are complementary and unordered, complementary and ordered or a set of alternative elements</xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:anyAttribute namespace="##other" processContents="lax" />
    </xs:complexType>
</xs:element>