Passing parameters to XSLT Stylesheet via .NET

You need to define the parameter within your XSLT and you also need to pass the XsltArgumentList as an argument to the Transform call:

private static void CreateHierarchy(string manID)
{
    string man_ID = manID;

    XsltArgumentList argsList = new XsltArgumentList();
    argsList.AddParam("Boss_ID", "", man_ID);

    XslCompiledTransform transform = new XslCompiledTransform(true);
    transform.Load("htransform.xslt");

    using (StreamWriter sw = new StreamWriter("output.xml"))
    {
        transform.Transform("LU AIB.xml", argsList, sw);
    }
}

Please note that the xsl:param must be defined below the xsl:stylesheet element:

<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
  <xsl:output method="xml" indent="yes" />

  <xsl:param name="Boss_ID"></xsl:param>

  <xsl:template match="OrgDoc">

     <!-- template body goes here -->

  </xsl:template>


</xsl:stylesheet>

---

This simple XSLT sample will create just a small output document containing one XML node with its contents set to the value of your parameter. Have a try:

<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
  <xsl:output method="xml" indent="yes" />
  <xsl:param name="Boss_ID"></xsl:param>

  <xsl:template match="https://stackoverflow.com/">
    <out>
      <xsl:value-of select="$Boss_ID" />
    </out>
  </xsl:template>

</xsl:stylesheet>