Question

I want to transform a markup like <root><a><c>CA</c></a></root> to <root juris="CA"><a><c>CA</c></a></root>

Answer 1

If you could specify more about the schema that is allowed, something more specific can be written. With what was given, something like this should work though:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
    <xsl:template match="/root">
        <xsl:copy>
            <xsl:attribute name="juris"><xsl:value-of select="./a/c"/></xsl:attribute>
            <xsl:copy-of select="*"/>
        </xsl:copy>
    </xsl:template>
</xsl:stylesheet>

As it stands, I would not be surprised if this led to issues with more complex inputs.