<xs:element name="CurvePoints" type="PolyLineType"><xs:annotation><xs:documentation>The CurvePoints element is the point list of the curve.</xs:documentation></xs:annotation></xs:element>
The id attribute is the QIF id of the feature zone, used for referencing.
Source
<xs:complexType name="FeatureZoneCurveIrregularType"><xs:annotation><xs:documentation>The FeatureZoneCurveIrregularType defines a feature zone as a curve</xs:documentation></xs:annotation><xs:complexContent><xs:extension base="FeatureZoneCurveBaseType"><xs:sequence><xs:element name="CurvePoints" type="PolyLineType"><xs:annotation><xs:documentation>The CurvePoints element is the point list of the curve.</xs:documentation></xs:annotation></xs:element></xs:sequence></xs:extension></xs:complexContent></xs:complexType>