In NETCONF telemetry subscriptions with Cisco IOS XE devices, the correct XML tag to complete the subscription is "period". This tag defines the interval in milliseconds at which the telemetry data will be collected and sent. The "period" tag is used to set a fixed time interval for data collection, as opposed to other options like "frequency" which would imply a rate of occurrence or "cadence" which refers to the flow or rhythm of events. References := ( Automating Cisco Enterprise Solutions Official Cert Guide )