@ambroisedlg - thanks very much for these suggestions. Indeed, I have 96 possible Slots in a day (though practically most Businesses are only open a fraction of the time).

Thanks for confirming that it’s reasonable to keep the Appointments as a list in Businesses. Yes - the user picks a date first, and then I want to show available slots.

I’m going to think more about your suggestion about using a focus group and repeating group. I haven’t done much with dates yet in Bubble, so wasn’t aware of the idea of looking for a date range overlap - will investigate this in more detail.

I’m still puzzled about why This Slot doesn’t seem to be available for use in a filter (when it is available for use in other conditions) as that would seem to be the easiest way to do what I’m trying to do - hoping for insight about this.