affiliatedTo 

The attribute affiliatedTo allows defining a specific notation of the index item. For example, if the
index item is 'houses' then it might be affiliated to 'house' so to have only one notation in the final index. If the
attribute is not set then the word(s) marked up as index item are taken for the final index.

Attribute Information

Used By

Attribute Group elml:IndexAttImp

Source 

<xs:attribute name="affiliatedTo" type="xs:string">
  <xs:annotation>
    <xs:documentation>The attribute affiliatedTo allows defining a specific notation of the index item. For example, if the index item is 'houses' then it might be affiliated to 'house' so to have only one notation in the final index. If the attribute is not set then the word(s) marked up as index item are taken for the final index.</xs:documentation>
  </xs:annotation>
</xs:attribute>

Sample