System.Xml.DocumentXmlWriter.StartState C# (CSharp) Méthode

        State StartState() {
            XmlNodeType nodeType = XmlNodeType.None;

            switch (type) {
                case DocumentXmlWriterType.InsertSiblingAfter:
                case DocumentXmlWriterType.InsertSiblingBefore:
                    XmlNode parent = start.ParentNode;
                    if (parent != null) { 
                        nodeType = parent.NodeType; 
                    }
                    if (nodeType == XmlNodeType.Document) {
                        return State.Prolog;
                    }
                    else if (nodeType == XmlNodeType.DocumentFragment)  {
                        return State.Fragment;
                    }
                    break;
                case DocumentXmlWriterType.PrependChild:
                case DocumentXmlWriterType.AppendChild:
                    nodeType = start.NodeType; 
                    if (nodeType == XmlNodeType.Document) {
                        return State.Prolog;
                    }
                    else if (nodeType == XmlNodeType.DocumentFragment)  {
                        return State.Fragment;
                    }
                    break;
                case DocumentXmlWriterType.AppendAttribute:
                    return State.Attribute;
                case DocumentXmlWriterType.ReplaceToFollowingSibling:
                    break;
            }
            return State.Content;
        }