diff --git a/doc/common/entities/openstack.ent b/doc/common/entities/openstack.ent
index f5655e7772..1ac5d37839 100644
--- a/doc/common/entities/openstack.ent
+++ b/doc/common/entities/openstack.ent
@@ -1,3 +1,9 @@
+
+<!-- Some useful entities borrowed from HTML -->
+<!ENTITY ndash  "&#x2013;">
+<!ENTITY mdash  "&#x2014;">
+<!ENTITY nbsp "&#160;">
+
 <!ENTITY CHECK '<inlinemediaobject xmlns="http://docbook.org/ns/docbook">
 <imageobject>
 <imagedata fileref="../common/figures/Check_mark_23x20_02.svg"