...sorry, there was an extra character in the XSL...use this instead if you are still trying this...this took only a few minutes to create with XMLSpy Stylesheet designer, in case you are interested.
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="
<xsl:template match="/">
<html>
<head />
<body>
<xsl:apply-templates />
</body>
</html>
</xsl:template>
<xsl:template match="pa" />
<xsl:template match="pif">
<xsl:for-each select="pa">
<xsl:for-each select="mi">
<xsl:for-each select="es">
<xsl:for-each select="e">
<xsl:for-each select="@disp_n">
<xsl:value-of select="." />
</xsl:for-each>
</xsl:for-each>
</xsl:for-each>
</xsl:for-each>
</xsl:for-each>
</xsl:template>
</xsl:stylesheet>