As a date like 9/11.No, I haven't heard that yet.
As in one of six? Or as a date like 9/11?
Much easier to name....
Trouble for us Brits is that we put the day first, month second, so we think of 1/6 as 1st June and 9/11 as 9th November.
But after 9/11 we did get more oriented to the real date of that terrorism.