Would be really dumb not to cancel transactions if equally "are not real" until they reach the 1440 confirmations.
I can pay you now, but will have to wait until 1440 to be effective confirmations. that is, it is not real.
and 1440 confirmations are 48 hours!
if you can not cancel, so I have to wait 1440 confirmations? make it immediately effective and voila!
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Oh, I should mention we do have something similar but in reverse: referenced transactions. It is possible to link transactions in such a way that if an original transaction is orphaned (or otherwise cancelled), the linked transaction (be it AE or a service provider's action, etc) can be automatically cancelled in return so a product or service isn't given for free.
Just FYI.