The global CharacteristicGroup element is the head of a substitution group. Any element that is a member of the group may be substituted for the CharacteristicGroup element anywhere the CharacteristicGroup element may be used in an instance file.
The id attribute is the QIF id of the characteristic group, used for referencing.
Source
<xs:element name="CharacteristicGroup" type="CharacteristicGroupType"><xs:annotation><xs:documentation>The global CharacteristicGroup element is the head of a substitution group. Any element that is a member of the group may be substituted for the CharacteristicGroup element anywhere the CharacteristicGroup element may be used in an instance file.</xs:documentation></xs:annotation></xs:element>