Using XSLT to compare two nodes and emit XML containing attribute indicating whether value was updated, added, or deleted

Question

Been programming front-end languages for a long time and I rarely encounter XSLT on a project. Well, here it is... We currently have some functions in our XSLT file that are comparing nodes and emitting XML that contains something like previousValue="Old value". This feature helps our users understand what changed when viewing the form.

Looking at the XML (below), I need to compare <ns1:OtherEducationTypeDesc> and emit XML correctly that states what the old value was.

I need it to look something like:

<EducationTypes>
    <EducationType Code="11">Engineering</EducationType>
    <EducationType Code="12" Value="New Value" PrevValue="Old Value">Other</EducationType>
</EducationTypes>

I tried to give as much information as possible but if you need anything else, let me know! Any assistance is appreciated!! Thanks!!

---

XSLT

<EducationTypes xmlns="omitted">
  <xsl:choose>
    <xsl:when test="$has-updates">
      <!--Get unchanged nodes-->
      <xsl:variable name="unchanged-nodes">
        <xsl:call-template name="intersection">
          <xsl:with-param name="nodes1" select="$educationType-nodes[1]/ns1:Code"/>
          <xsl:with-param name="nodes2" select="$educationType-nodes[last()]/ns1:Code"/>
        </xsl:call-template>
      </xsl:variable>
      <xsl:call-template name="education-codes">
        <xsl:with-param name="node-set" select="msxsl:node-set($unchanged-nodes)/ns1:Code"/>
        <xsl:with-param name="otherText" select="$educationType-nodes[last()]/ancestor::ns1:ProgramInfo/ns1:OtherEducationTypeDesc"/>
      </xsl:call-template>

      <!--Get added nodes-->
      <xsl:variable name="added-nodes">
        <xsl:call-template name="difference">
          <xsl:with-param name="nodes1" select="$educationType-nodes[last()]/ns1:Code"/>
          <xsl:with-param name="nodes2" select="$educationType-nodes[1]/ns1:Code"/>
        </xsl:call-template>
      </xsl:variable>
      <xsl:call-template name="education-codes">
        <xsl:with-param name="node-set" select="msxsl:node-set($added-nodes)/ns1:Code"/>
        <xsl:with-param name="otherText" select="$educationType-nodes[last()]/ancestor::ns1:ProgramInfo/ns1:OtherEducationTypeDesc"/>
        <xsl:with-param name="status" select="'added'"/>
      </xsl:call-template>

      <!--Get deleted nodes-->
      <xsl:variable name="deleted-nodes">
        <xsl:call-template name="difference">
          <xsl:with-param name="nodes1" select="$educationType-nodes[1]/ns1:Code"/>
          <xsl:with-param name="nodes2" select="$educationType-nodes[last()]/ns1:Code"/>
        </xsl:call-template>
      </xsl:variable>
      <xsl:call-template name="education-codes">
        <xsl:with-param name="node-set" select="msxsl:node-set($deleted-nodes)/ns1:Code"/>
        <xsl:with-param name="otherText" select="$educationType-nodes[last()]/ancestor::ns1:ProgramInfo/ns1:OtherEducationTypeDesc"/>
        <xsl:with-param name="status" select="'deleted'"/>
      </xsl:call-template>
    </xsl:when>

    <xsl:otherwise>
      <xsl:call-template name="education-codes">
        <xsl:with-param name="node-set" select="$educationType-nodes/ns1:Code" />
        <xsl:with-param name="otherText" select="$educationType-nodes/ancestor::ns1:ProgramInfo/ns1:OtherEducationTypeDesc"/>
      </xsl:call-template>
    </xsl:otherwise>
  </xsl:choose>
</EducationTypes>

---

XML

<?xml version="1.0" encoding="ISO-8859-1"?>
<ns1:ProgramInfo>
  <ns1:RecognizedDegrees>false</ns1:RecognizedDegrees>
    <ns1:EducationCodes>
      <ns1:Code>01</ns1:Code>
      <ns1:Code>02</ns1:Code>
      <ns1:Code>09</ns1:Code>
      <ns1:Code>10</ns1:Code>
      <ns1:Code>12</ns1:Code>
    </ns1:EducationCodes>
    <ns1:OtherEducationTypeDesc>Old Description</ns1:OtherEducationTypeDesc>
    <ns1:DegreeCodes>
      <ns1:Code>03</ns1:Code>
      <ns1:Code>06</ns1:Code>
      <ns1:Code>07</ns1:Code>
    </ns1:DegreeCodes>
    <ns1:OtherDegreeDesc></ns1:OtherDegreeDesc>
    <ns1:EducationLevels>
      <ns1:Code>08</ns1:Code>
    </ns1:EducationLevels>
    <ns1:OtherEducationLevelDesc></ns1:OtherEducationLevelDesc>
</ns1:ProgramInfo>

<ns1:ProgramInfo>
    <ns1:RecognizedDegrees>false</ns1:RecognizedDegrees>
    <ns1:EducationCodes>
      <ns1:Code>01</ns1:Code>
      <ns1:Code>02</ns1:Code>
      <ns1:Code>09</ns1:Code>
      <ns1:Code>10</ns1:Code>
      <ns1:Code>12</ns1:Code>
    </ns1:EducationCodes>
    <ns1:OtherEducationTypeDesc>New Description</ns1:OtherEducationTypeDesc>
    <ns1:DegreeCodes>
      <ns1:Code>03</ns1:Code>
      <ns1:Code>06</ns1:Code>
      <ns1:Code>07</ns1:Code>
    </ns1:DegreeCodes>
    <ns1:OtherDegreeDesc></ns1:OtherDegreeDesc>
    <ns1:EducationLevels>
      <ns1:Code>08</ns1:Code>
    </ns1:EducationLevels>
    <ns1:OtherEducationLevelDesc></ns1:OtherEducationLevelDesc>
  </ns1:ProgramInfo>