.. _conf.dm.tools_hist.maint:

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History Maintenance
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The History Maintenance tool allows you to manage and delete tag historical data and event history. You can use it to clear all historical data for tags or events, update current tag values, or selectively delete specific tag or event history records.

To use the History Maintenance tool, follow the steps below:

1. Choose :menuselection:`Configuration --> Data Management --> Tools --> History Maintenance` from the menu.
2. Choose one of the following options:
     
   - **Clear All Tag History**: Deletes all historical data for all tags.
   - **Set Current Value to the Last Historian Value for ALL Tags**: Updates the current value of all tags to their last recorded historical value.
   - **Clear ALL Event History**: Deletes all event history data.
   - **Delete Selected Tag History**: Deletes historical data for selected tags.
   - **Delete Selected Event History**: Deletes event history for selected events.

3. Confirm the deletion or update action in the dialog box to proceed. For deleting selected tag or event history, make sure to select the specific tags or events first.