Ah. Thanks for the insight.
The “list” is basically a list of phone numbers. No names. Men have only female numbers, female only males. When someone wants to have sex, they call a number, and say “Are you free tonight?” If the answer is no, nothing more is said. If the answer is yes, a time and place are agreed on, and a sexual encounter ensues. No names, no details, no personal talk. The only rule seems to be that whoever initiates the call is responsible for paying for the room.
That’s it. You can be introduced to the list by a friend, and that person is responsible for telling you the rules.
The people involved were all pretty high power individuals that just liked the non-committal sex. All seemed to have money.
This sounds like it would be impossible to set up in the real world, but it made me wonder if anyone had ever heard of something like this IRL.