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Publish layout with comment lets you add a comment to the published version. All comments are visible in the version history in the left-hand menu (accessible through the three-line icon).
Save as draft with comment lets you add a comment to the current draft version. This comment is visible in the version history in the left-hand menu (accessible through the three-line icon). Note that when you publish a new version of the layout, the draft and its comment will disappear from the version history overview.
Discard current draft takes you back to the layout that was last published.
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Restore, export, or delete a previous layout version
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