Prof. Daniel Abadi talks about the two meanings of consistency in this blogpost: https://dbmsmusings.blogspot.com/2019/07/overview-of-consistency-levels-in.html

Prof. Daniel Abadi talks about the two meanings of consistency in this blogpost: https://dbmsmusings.blogspot.com/2019/07/overview-of-consistency-levels-in.html https://dbmsmusings.blogspot.com/2019/07/overview-of-consist... I'd argue that in your second case, there's no consistency "external" to the system; you've now defined a larger, distributed system that includes your external parties, and now you're in consistency-as-in-CAP territory, rather than consistency-as-in-ACID.