Extract input filename

Input files
1. input.xml
2. input_meta.xml

command line
java -jar saxon8.jar input.xml x.xsl >c.xml

Stylesheet
<xsl:variable name="filename" select="document('input_meta.xml')" />
<xsl:template match="/">
	<doi>
      <xsl:copy-of select="$filename/doi/text()" />
	</doi>
</xsl:template>

Thanks in advance.
JSR