The defer having to do with allowing someone else to decide or choose something, or with agreeing to follow someone else’s decision, tradition, etc., (as in “He deferred to his parents’ wishes”) comes from the Latin verb dēferre, meaning “to bring down, convey, transfer, submit....
That then sets a special value in the item which includes a deferred for when the history crawl has been completed and a callback to set values on the item to replace the special values with the real values from the history. This seemed what returning a Deferred was designed for. What is...