diff --git a/poky/documentation/ref-manual/ref-manual-customization.xsl b/poky/documentation/ref-manual/ref-manual-customization.xsl
index c58dd90..3181f61 100644
--- a/poky/documentation/ref-manual/ref-manual-customization.xsl
+++ b/poky/documentation/ref-manual/ref-manual-customization.xsl
@@ -1,4 +1,6 @@
 <?xml version='1.0'?>
+<!--SPDX-License-Identifier: CC-BY-2.0-UK-->
+
 <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns="http://www.w3.org/1999/xhtml" xmlns:fo="http://www.w3.org/1999/XSL/Format" version="1.0">
 
   <xsl:import href="http://downloads.yoctoproject.org/mirror/docbook-mirror/docbook-xsl-1.76.1/xhtml/docbook.xsl" />