This is an idea that was lying around in one old issue in Jour Jira instance (TMP-4055).
Here is the text from the issue:
Some users want to be able to close the Timeline for editing, similar as it can be done for Timesheets (in the period management). They want to be able to have a reference for plans created in the past.
Currently the period management in Tempo is only used in Timesheets.
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