+To get two levels in the index at the back, add entries like this to
+the docbook source:
+
+ <indexterm>
+ <primary>artists</primary>
+ <secondary>publicity rights on images of</secondary>
+ </indexterm>
+
+To index a range of paragrams/pages:
+
+ <indexterm id="idxexchap" class='startofrange'>
+ <primary>Example Chapter</primary></indexterm>
+ ...
+ <indexterm startref="idxexchap" class="endofrange"/>
+