Example 1 of <xsl:attribute> 

This example copies the <myElement> element and adds a copied attribute with the value "true".

XML File (myelem.xml)

<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="attrcopied.xsl" ?>
<root>
   <myElement>My Data</myElement>
   <myElement>My Other Data</myElement>
</root>

XSLT File (attrcopied.xsl)

<?xml version="1.0"?>
<xsl:stylesheet version="1.0"
      xmlns:xsl="http://www.w3.org/1999/XSL/Transform" >

<xsl:template match="myElement">
  <xsl:copy>
    <xsl:attribute name="copied">true</xsl:attribute>
    <xsl:apply-templates />
  </xsl:copy>
</xsl:template>

</xsl:stylesheet>

Output

This is the formatted output:

My DataMy Other Data

The following is the processor output, with line breaks added for clarity.

<?xml version="1.0"?>

<myElement copied="true">My Data</myElement>

<myElement copied="true">My Other Data</myElement>