The plan mode allows you to work and plan using a third dimension. This mode presents the backlog area (left part) and the planner area (right part). The issues flow from the backlog to the planner, simply by dragging them. When you need to unplan an issue in the planner, you don't need to remember where it was, just hover the appropriate issue and a "X" will appear. This "X" moves the issue to its original place.
Backlog
Planner
Planning your Sprints
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