Generally a code of conduct can be useful … when it is needed.
To restate my opinion on this:
Imagine you give a fresh married couple a gift card for a gift card for a marriage crisis advisor ...
What kind of ideas do you plant in their heads? What kind of image you produce of them by that, for them. How do you guide how they think about themselve, how they invent their marriage together? Was it a mistake to get married?
Imagine you give them tickets for a world trip and 6 months off, instead. Give them them means to develop a healthy relationship!
When things have gone wrong its time for the crisis advisor gift card - and then not too late. But before anything happened it is just an accusation. Saying: "I suspect YOU to behave badly."
I really like what @Nadia says: Just add one sentence saying something like:
"The OSCEdays is a space where we treat one another respectfully, every voice can be heard, equally."
This is a beautiful spin. And it is likely to attract the right people and inspire good action. This is the world trip.
It is the way we communicate that produces the culture! When we are inclusive, and I think we are, culture will be like this. And in the best case we will never need a Code of Conduct.
In my opinion a Code of Conduct is a band aid for a broken culture. If I see one, I think, ah, things have gone wrong here - the culture is fucked up. But nothing like this happened here, so far.