TypeOfFrameRef in ClassInFrameGroup makes uncommon NeTEx reference

[skinkie]

        <xsd:group name="ClassInFrameGroup">
                <xsd:annotation>                
                        <xsd:documentation>Elements for a CLASS IN FRAME.</xsd:documentation>
                </xsd:annotation>                       
                <xsd:sequence>
                        <xsd:element name="ClassRefType" type="ClassRefTypeEnumeration" default="members" minOccurs="0">
                                <xsd:annotation>
                                        <xsd:documentation>Nature of reference: Members | Member References | All.</xsd:documentation>
                                </xsd:annotation>
                        </xsd:element>  
                        <xsd:element name="TypeOfFrameRef" type="TypeOfFrameIdType" minOccurs="0">
                                <xsd:annotation>
                                        <xsd:documentation>Type of FrAMe containing CLass.</xsd:documentation>
                                </xsd:annotation>
                        </xsd:element>

I would expect:

        <xsd:group name="ClassInFrameGroup">
                <xsd:annotation>
                        <xsd:documentation>Elements for a CLASS IN FRAME.</xsd:documentation>
                </xsd:annotation>
                <xsd:sequence>
                        <xsd:element name="ClassRefType" type="ClassRefTypeEnumeration" default="members" minOccurs="0">
                                <xsd:annotation>
                                        <xsd:documentation>Nature of reference: Members | Member References | All.</xsd:documentation>
                                </xsd:annotation>
                        </xsd:element>
                        <xsd:element ref="TypeOfFrameRef" minOccurs="0"> 
                                <xsd:annotation>
                                        <xsd:documentation>Type of Frame containing Class.</xsd:documentation>
                                </xsd:annotation>
                        </xsd:element>