diff --git a/asciidoc/install-asciidoc.adoc b/asciidoc/install-asciidoc.adoc
index 943fdb9..63f163c 100644
--- a/asciidoc/install-asciidoc.adoc
+++ b/asciidoc/install-asciidoc.adoc
@@ -64,6 +64,7 @@ All you need to preview an AsciiDoc document in a web browser is to install the
 Then you can see the AsciiDoc file rendered as HTML just by visiting it!
 
 
+
 .Live Preview
 image:tiled-editor-and-web-preview.png[alt="Swarmlab"]
 
diff --git a/asciidoc/test.txt b/asciidoc/test.txt
new file mode 100644
index 0000000..95e1bc4
--- /dev/null
+++ b/asciidoc/test.txt
@@ -0,0 +1,25 @@
+////
+Included in:
+
+- user-manual: callouts: XML-friendly callouts
+////
+
+XML doesn't have line comments, so our "`tuck the callout behind a line comment`" trick doesn't work here.
+To use callouts in XML, you must place the callout's angled brackets around the the XML comment and callout number.
+
+Here's how it appears in a listing:
+
+[source,subs=specialcharacters]
+....
+include::ex-callout.adoc[tag=source-xml]
+....
+
+Here's how it looks when rendered:
+
+====
+include::ex-callout.adoc[tag=source-xml]
+====
+
+Notice the comment has been replaced with a circled number that cannot be selected (if not using font icons it will be
+rendered differently and selectable).
+Now both you and the reader can copy and paste XML source code containing callouts without worrying about errors.