In reply to David.

The Tickler File is basically a way to postpone things into the future (like a boomerang which comes back at a certain date). These are things that you can't or don't want to work on at the moment, but you want to reconsider them at a later date.

I recommend keeping a separate Tickler list because you can move anything here with a date attached (on hold projects, ideas etc.). The Schedule list collects all reminders from all your lists (not just the Tickler) so you can see the big picture with all your due tasks and upcoming things neatly organized in a calendar.