<?xml version="1.0"?>

<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

<xsl:output method="xml" encoding="utf-8"/>

<xsl:template match="@*|node()">
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<xsl:template match="*:s|*:head">
  <xsl:variable name="elemName" select="name()"/>
  <xsl:variable name="docPos">
    <xsl:choose>
      <xsl:when test="$elemName = 's'">
        <xsl:value-of select="count(./preceding::*:s) + 1"/>
	    </xsl:when>
      <xsl:when test="$elemName = 'head'">
        <xsl:value-of select="count(./preceding::*:head) + 1"/>
      </xsl:when>
	    <xsl:otherwise></xsl:otherwise>
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  <xsl:copy>
    <xsl:attribute name="xml:id">
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    <xsl:apply-templates select="@*|node()"/>
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</xsl:stylesheet>