# Invalidate Value Some Datastreams have meaningful value only when it is fresh (updated recently). For such Datastreams you can setup the invalidation period and invalidate the value according to the selected policy. For example, you made an thermometer and interested in the current temperature outside the window. Thermometer wakes up hourly and sends the current temperature to the display widget on the web or mobile. Let's assume you made a setup with the 2 hours invalidation period and selected `No Data` policy. Due to any malfunction your device could stop sending the updates. Without the invalidation period you will always see the latest value on the screen. However, with invalidation period after 2 hours since the last update - value will be invalidated with `No Data` label. So end users will not be confused with the "freezed latest value". Currently you can select one of the following invalidation policies: * **Nothing** - widget will be empty and will show nothing * **Default** - widget will be filled with the default value of the data stream if it is present * **No Data** - text `No Data` will be showed * **Empty** - text `Empty` will be showed * **--** - text `--` will be showed ![](/files/-MSgwj1bTaMTPpqSlm3P) --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.blynk.io/en/blynk.console/templates/datastreams/datastreams-common-settings/invalidate-value.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.