diff --git a/build/identity.xsl b/build/identity.xsl
new file mode 100644
index 00000000..82652c15
--- /dev/null
+++ b/build/identity.xsl
@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+
+	identity.xsl
+	
+	Identity transform.
+	
+	Author: Ian A. Young <ian@iay.org.uk>
+
+-->
+<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
+
+	<!--By default, copy text blocks, comments and attributes unchanged.-->
+	<xsl:template match="text()|comment()|@*">
+		<xsl:copy/>
+	</xsl:template>
+	
+	<!--By default, copy all elements from the input to the output, along with their attributes and contents.-->
+	<xsl:template match="*">
+		<xsl:copy>
+			<xsl:apply-templates select="node()|@*"/>
+		</xsl:copy>
+	</xsl:template>
+	
+</xsl:stylesheet>