The required index attribute is an index identifying a zone section plane within the SectionPlanes set.
Source
<xs:element name="SectionPlane" type="ZoneSectionPlaneType" maxOccurs="unbounded"><xs:annotation><xs:documentation>Each SectionPlane element is a section plane.</xs:documentation></xs:annotation></xs:element>
The required n attribute is the number of SectionPlane elements in this set.
Source
<xs:complexType name="ZoneSectionPlanesType"><xs:annotation><xs:documentation>The ZoneSectionPlanesType is a collection of zone section planes.</xs:documentation></xs:annotation><xs:sequence><xs:element name="SectionPlane" type="ZoneSectionPlaneType" maxOccurs="unbounded"><xs:annotation><xs:documentation>Each SectionPlane element is a section plane.</xs:documentation></xs:annotation></xs:element></xs:sequence><xs:attribute name="n" type="NaturalType" use="required"><xs:annotation><xs:documentation>The required n attribute is the number of SectionPlane elements in this set.</xs:documentation></xs:annotation></xs:attribute></xs:complexType>
<xs:attribute name="n" type="NaturalType" use="required"><xs:annotation><xs:documentation>The required n attribute is the number of SectionPlane elements in this set.</xs:documentation></xs:annotation></xs:attribute>