diff --git a/tests/sample-documents/DocBookSGML-Larger/index.sgml b/tests/sample-documents/DocBookSGML-Larger/index.sgml
index 312584b..d571fad 100644
--- a/tests/sample-documents/DocBookSGML-Larger/index.sgml
+++ b/tests/sample-documents/DocBookSGML-Larger/index.sgml
@@ -1,5 +1,33 @@
-<index>
+<index id='doc-index'>
 
 <!-- This file was produced by collateindex.pl.         -->
 <!-- Remove this comment if you edit this file by hand! -->
+<!-- ULINK is abused here.
+
+      The URL attribute holds the URL that points from the index entry
+      back to the appropriate place in the output produced by the HTML
+      stylesheet. (It's much easier to calculate this URL in the first
+      pass.)
+
+      The Role attribute holds the ID (either real or manufactured) of
+      the corresponding INDEXTERM.  This is used by the print backends
+      to produce page numbers.
+
+      The entries below are sorted and collated into the correct order.
+      Duplicates may be removed in the HTML backend, but in the print
+      backends, it is impossible to suppress duplicate pages or coalesce
+      sequences of pages into a range.
+-->
+
+<title>Index</title>
+
+<indexdiv><title>T</title>
+
+<indexentry>
+  <primaryie>Text,
+    <ulink url="t1.htm#INTRO" role="AEN22">Introduction</ulink>
+  </primaryie>
+</indexentry>
+
+</indexdiv>
 </index>