The optional xId attribute is a reference to the id of a QIF object in an external document. A QIF object in an external QIF document can be referenced by using references to two QIF ids: the id of the external document reference of type ExternalQIFDocumentReferenceType found in the local document and the id of the object found in the external document.
Source
<xs:element name="MeasurePointId" type="PointSetReferenceSingleType"><xs:annotation><xs:documentation>The MeasurePointId element is the index of a single point in a measured point set with the specified QIF id.</xs:documentation></xs:annotation></xs:element>
The Deviation element is the deviation of the individual measurement point in the direction of the surface or curve normal. It is positive if the deviation is in the direction of the normal vector and negative if the deviation is in the direction opposite the normal vector.
<xs:element name="Deviation" type="LinearValueType"><xs:annotation><xs:documentation>The Deviation element is the deviation of the individual measurement point in the direction of the surface or curve normal. It is positive if the deviation is in the direction of the normal vector and negative if the deviation is in the direction opposite the normal vector.</xs:documentation></xs:annotation></xs:element>
<xs:complexType name="PointDeviationType"><xs:annotation><xs:documentation>The PointDeviationType defines the deviation of a measurement point from nominal.</xs:documentation></xs:annotation><xs:sequence><xs:element name="MeasurePointId" type="PointSetReferenceSingleType"><xs:annotation><xs:documentation>The MeasurePointId element is the index of a single point in a measured point set with the specified QIF id.</xs:documentation></xs:annotation></xs:element><xs:element name="Deviation" type="LinearValueType"><xs:annotation><xs:documentation>The Deviation element is the deviation of the individual measurement point in the direction of the surface or curve normal. It is positive if the deviation is in the direction of the normal vector and negative if the deviation is in the direction opposite the normal vector.</xs:documentation></xs:annotation></xs:element></xs:sequence></xs:complexType>