You'll never get this right, even if you had all of this info, because as mjevans points out[0] to make it work you need to know: > P) The event is at a precis

You'll never get this right, even if you had all of this info, because as mjevans points out[0] to make it work you need to know: > P) The event is at a precise internationally recognized moment (better for co-ordination globally). > R) The event is in local time (like a lunch date) and expected to remain colloquially fixed. In the case you mention, it's somewhat arguable that the burden of changing the colloquially fixed dates (R) falls on the citizens of footopia, in the same way as changing the time of a purely mechanical clock also would. caveat emptor. [0] https://news.ycombinator.com/item?id=13206671 https://news.ycombinator.com/item?id=13206671