xslt: traverse chain of ancestors in reverse order

suppose I have the following xml-document:

<?xml version="1.0"?>
<xs:schema xmlns:xs="http://ift.tt/tphNwY">
  <xs:element name="FirstLevel">
    <xs:unique name="uniqueL2inL1">
      <xs:selector xpath="SecondLevel" />
      <xs:field xpath="@Name" />
    </xs:unique>
  </xs:element>
  <xs:element name="SecondLevel">
    <xs:unique name="uniqueL3inL2">
      <xs:selector xpath="ThirdLevel" />
      <xs:field xpath="@Name" />
    </xs:unique>
  </xs:element>
  <xs:element name="ThirdLevel">
    <xs:unique name="uniqueL4inL3">
      <xs:selector xpath="FourthLevel" />
      <xs:field xpath="@Name" />
    </xs:unique>
  </xs:element>
  <xs:element name="FourthLevel"/>
</xs:schema>

What possibilities are there to get the "chain" of unique-definitions from the ThirdLevel element up to the document root in a backward ordering?

The resulting output I wanna have for ThirdLevel for example:

FirstLevel
SecondLevel

I got a solution which outputs them in the wrong order:

<xsl:stylesheet version="2.0"
  xmlns:xsl="http://ift.tt/tCZ8VR"
  xmlns:xs="http://ift.tt/tphNwY" >
  <xsl:output method="text" />
  <xsl:template match="xs:element">
    <xsl:result-document href="chain_{@name}">
      <xsl:variable name="element-name" select="@name"/>
      <xsl:variable name="parent-name" select="//xs:unique/xs:selector[@xpath=$element-name]/@xpath"/>
      <xsl:if test="$parent-name != ''">
        <xsl:call-template name="mytemplate">
          <xsl:with-param name="unique-block" select="//xs:unique/xs:selector[@xpath=$element-name]/.."/>
        </xsl:call-template>
      </xsl:if>
    </xsl:result-document>
  </xsl:template>
  <xsl:template name="mytemplate">
    <xsl:param name="unique-block"/>
    <xsl:variable name="parent-name" select="$unique-block/../@name"/>
    <xsl:value-of select="$parent-name"/>
    <xsl:variable name="unique-selector" select="//xs:unique/xs:selector[@xpath=$parent-name]/@xpath"/>
    <!-- evaluate and recurse, if needed: -->
    <xsl:if test="$unique-selector != ''">
      <xsl:call-template name="mytemplate">
        <xsl:with-param name="unique-block" select="//xs:unique/xs:selector[@xpath=$parent-name]/.." />
      </xsl:call-template>
    </xsl:if>
  </xsl:template>
</xsl:stylesheet>

Which outputs:

saxonb-xslt -ext:on -s:minimal.xsd -xsl:minimal.xslt && cat chain_ThirdLevel

SecondLevel
FirstLevel

But the approach itself feels just wrong to me... Some tips or improvements?

Greetings