Read a OneNote hierarchy in C# ....

Program.cs

static void Main(string[] args) {

        // OneNote 2013 Schema namespace.
        string strNamespace = "http://schemas.microsoft.com/office/onenote/2013/onenote";
        string outputXML;
        Application onApplication = new Application();
        onApplication.GetHierarchy(null, HierarchyScope.hsSections, out outputXML);
        
        // Load a new XmlDocument.
        XmlDocument xmlDoc = new XmlDocument();
        xmlDoc.LoadXml(outputXML);
        XmlNamespaceManager nsmgr = new XmlNamespaceManager(xmlDoc.NameTable);
            nsmgr.AddNamespace("one", strNamespace);
            
        // Search for the section named "Sample_Section".
        XmlNode xmlNode = xmlDoc.SelectSingleNode("//one:Section[@name='Sample_Section']", nsmgr);
        
        // Prompt for a new section title.
        System.Console.Write("Please enter a new title for the section: ");
        string input = System.Console.ReadLine();
        xmlNode.Attributes["name"].Value = input;
        // Update the section with the new title.
        onApp.UpdateHierarchy(xmlNode.OuterXml);
        System.Console.Write("Done!\n");
    }

Just a handy snippet I wanted to save and import programmatically for examples ...