As you said, many XSLT programming situations could be
equivanetly handled by for-each&  apply-templates.

..
<xsl:variable name="a">...</xsl:variable>
..
<xsl:variable name="z">...</xsl:variable>
...
<xsl:for-each select="foo">
  body
</xsl:for-each>

.
<xsl:variable name="a">...</xsl:variable>
..
<xsl:variable name="z">...</xsl:variable>
...
<xsl:apply-templates select="foo" mode="unique-d">
  <xsl:with-param name="a" select="$a"/>
  <xsl:with-param name="z" select="$z"/>
</xsl:apply-templates>

<xsl:template match="/|node()" mode="unique-id">
  <xsl:param name="a"/>
  <xsl:param name="z"/>
  body
</xsl:template>

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