This doesn't seem to be specificed in the docs and the FAQ.

I see this suggested in https://meta.stackexchange.com/questions/285889/lets-plan-the-second-iteration-of-the-stack-exchange-quality-project/285911#285911 (10.2016) and mentioned as an existing feature (!) in https://meta.stackexchange.com/questions/67968/un-delete-count-off/67970#67970 (10.2010).