Sub SmartDocs_UpdateReusableVariable(variableName As String, variableValue As String)

    Dim namespaceUri As String
    namespaceUri = "http://www.thirtysix.net/smartdocs/reusableVariables"

    ' Get the custom XML part that contains SmartDocs reusable variables.
    
    Dim xmlPart As CustomXMLPart
    Set xmlPart = ActiveDocument.CustomXMLParts.SelectByNamespace(namespaceUri)(1)
    
    ' Ensure custom XML part was found.
    
    If xmlPart Is Nothing Then
        Exit Sub
    End If
    
    ' Get prefix for namespace.
    
    Dim prefix As String
    prefix = xmlPart.NamespaceManager.LookupPrefix(namespaceUri)
    
    ' Create XPath to XML node that contains SmartDocs reusable variable.
    
    Dim xpath As String
    
    xpath = "//{prefix}:ReusableVariable[{prefix}:Name='{name}']/{prefix}:Value"
    xpath = Replace(xpath, "{prefix}", prefix)
    xpath = Replace(xpath, "{name}", variableName)
    
    ' Get the XML node.
    
    Dim xmlNode As CustomXMLNode
    Set xmlNode = xmlPart.DocumentElement.SelectSingleNode(xpath)
    
    If xmlNode Is Nothing Then
        Exit Sub
    End If
    
    ' Update the value of the node.
    
    xmlNode.Text = variableValue

End Sub