code: function(options) {
          var node = this.writeNode("sos:GetObservation", options);
          node.setAttribute("xmlns:om", this.namespaces.om);
          node.setAttribute("xmlns:ogc", this.namespaces.ogc);
          this.setAttributeNS(
              node, this.namespaces.xsi,
              "xsi:schemaLocation", this.schemaLocation
          );
          return OpenLayers.Format.XML.prototype.write.apply(this, [node]);
      }
docs: Method: write
  
  Parameters:
  options - {Object} Optional object.
  
  Returns:
  {String} An SOS GetObservation request XML string.