I created a BS4 Component called Card With Tab Navigation. I used the BS4 Card With Navigation as it's base in which I added in tab swapping functionality. I was working in BS4 during it's build and saved it to my library. Hovering over the Component in my Library shows the Badge as BS4 and hovering over that says made with Bootstrap 4. I shared it for the Online community.
However, in the Online community it displays a BS3 Badge, yet in the Studio tab it displays a BS4 Badge. I would assume it gets it's Badge from the version of the interface in which it was created and shared through not anything in the HTML it's self. Although, the HTML isn't necessarily completely semantic it does follow http://getbootstrap.com/docs/4.0/components/card/#navigation and http://getbootstrap.com/docs/4.0/components/navs/#javascript-behavior in a melding of the 2 components though. With the role and aria attributes etc...
Saj