code: function createFESR(oInteraction, oFESRHandle) {
  		return [
  			format(ROOT_ID, 32), // root_context_id
  			format(sFESRTransactionId, 32), // transaction_id
  			format(oInteraction.navigation, 16), // client_navigation_time
  			format(oInteraction.roundtrip, 16), // client_round_trip_time
  			format(oFESRHandle.timeToInteractive, 16), // end_to_end_time
  			format(oInteraction.completeRoundtrips, 8), // completed network_round_trips
  			format(sPassportAction, 40), // passport_action
  			format(oInteraction.networkTime, 16), // network_time
  			format(oInteraction.requestTime, 16), // request_time
  			format(CLIENT_OS, 20), // client_os
  			"SAP_UI5" // client_type
  		].join(",");
  	}
docs: creates mandatory FESR header string