Thomas is right - you can just use ESC

But we are talking about lines of text in a single note.. And I get the impression that you're talking about adding a new field to the note itself - do I understand correctly?

Remember that we are talking about lines of text within a single note. As items are marked as done, you can just move them to the bottom for example.

IMO this is much better handled by a number of hierarchical tags: Type/Regular, Type/NextAction, Status/New, Status/WaitingFor, Status/OnHold, Status/Done, Prio/Today, Prio/ThisWeek, Prio/Someday, etc.