The CCfC idea is a more practical alternative to CDCC idea, also dedicated to data minimization.
It plays a role when the highest/most dangerous peak of infections is over.
Core idea is that every event / market gets an ID which it publicly shows. As a spectator at the event or user of the market you remember the ID (assisted by some kind of culture technique).
For every new tested-positive case of Covid-19 the events/markets where the patient has been will be rated as endangered and the correspondent IDs will be publicly announced.
As a citizen you have the obligation to watch the ID announcements and go into quarantaine when one of your IDs match.
I don't want to tell you too much prosa - here's an "FAQ" on the concept (although no-one had ever chance to ask any question at this time of writing):
That is because a "Zukunftsstadt" (German project of better cities, in this case developed on the Dresden sessions) project I former participated in has this name. It is about Tickets/IDs which look like this: #CC4922
See http://id.cityconcierge.org for an impression what tickets could look like.
No. Cititzen have the obligation to remember the number, but at no point they have to tell anyone. (Except when they get tested positive)
Anyway - the convenient use smartphone applications (instead of paper lists), can be an indirect danger for privacy anyway, but fewer than the discussed variants of phone tracking or dedicated contact tracing teams..
No. The administration just provides a bunch of uniqe IDs per interested person, without actual contextual information.
For the sake of usability it may make sense to add some event information to the IDs, but this is not a requirement for the CCfC to work.
Probably a daily announcement makes most sense. It could look like the municipal administration announcing the endangered IDs at 19:30 on web and radio/TV. This is comparable to bingo or lottery.