diff -r 9e37178084c5 -r a8a8eca85801 src/HOL/ROOT
--- a/src/HOL/ROOT	Mon Sep 21 11:31:56 2015 +0200
+++ b/src/HOL/ROOT	Mon Sep 21 14:44:32 2015 +0200
@@ -169,6 +169,15 @@
   options [document = false]
   theories EvenOdd
 
+session "HOL-Data_Structures" in Data_Structures = HOL +
+  options [document_variants = document]
+  theories [document = false]
+    "Less_False"
+  theories
+    Tree_Set
+    Tree_Map
+  document_files "root.tex"
+
 session "HOL-Import" in Import = HOL +
   theories HOL_Light_Maps
   theories [condition = HOL_LIGHT_BUNDLE] HOL_Light_Import