Admin Center: HTML Settings: How should we use the new Markup filtering field input?

How should we use the new Markhup filtering input field?

This is not very clear at a first glance. I entered for instance: "b; strong" in order to remove all bold and strong tags... but this fails. What is the separator?

I am not sure we should just put an input form field. Perhaps a "add" button which is launching a new pop-up to enter a tag (and whioch clearly explain if you need to enter the bracket or not, etc... would be more adequate.