diff --git a/reference/filter/book.xml b/reference/filter/book.xml
index 0218c077e3..3419ed64c2 100644
--- a/reference/filter/book.xml
+++ b/reference/filter/book.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.3 $ -->
+<!-- $Revision: 1.4 $ -->
 <!-- Purpose: basic.vartype -->
 
 <book xml:id="book.filter" xmlns="http://docbook.org/ns/docbook">
@@ -205,7 +205,7 @@
         <entry></entry>
         <entry></entry>
         <entry>
-         Remove all characters except digits and <literal>+-</literal>.
+         Remove all characters except digits, plus and minus sign.
         </entry>
        </row>
        <row>