public virtual void Write( System.Xml.XmlWriter xmlWriter, TimeSpan duration, string elementName, string elementNamespace ) { if (duration == null) throw new ArgumentNullException("duration"); this._WriteStartElement(xmlWriter, elementName, elementNamespace); this._WriteAttribute ( xmlWriter, "interval", String.Empty, duration.ToISO8601(), String.Empty ); this._WriteEndElement(xmlWriter); }