Add `m` attribute to all leaf nodes

add_m_attribute.xsl

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
    xmlns:xs="http://www.w3.org/2001/XMLSchema" exclude-result-prefixes="xs" version="2.0"
    xmlns:d="http://nihr.ac.uk/nhic/ICU/UCL/finalv8.3.2">

    <xsl:output indent="yes"/>
    <xsl:strip-space elements="*"/>
    <xsl:variable name="dateNow" select="format-date(current-date(), '[Y0001]-[M01]-[D01]')"/>

    <xsl:template match="node()|@*">
        <xsl:copy>
            <xsl:apply-templates select="node()|@*"/>
        </xsl:copy>
    </xsl:template>
    
    <xsl:template match="//*[starts-with(name(), 'd:NIHR_HIC_ICU_')]">
        <xsl:variable name="elementName" select="name()"/>
        <xsl:element name="{$elementName}">
               <xsl:attribute name="m">
                   <xsl:value-of select="$dateNow" />
               </xsl:attribute>
            <xsl:apply-templates select="@*|node()"/>
        </xsl:element>
    </xsl:template>

</xsl:stylesheet>