http://www.creationkit.com/Furniture

Its not listed here and its not "interaction keyword" they are mentioning.

From what I understand an "marker keyword" is supposed to either add keyword to the actor using marker or is keyword "entry" for that specific marker.

The thing is that none of the above works for me...

- I added some keywords to vanilla furnitures -> could still use them

- Removed keywords from the existsing ones (that had them) -> didnt change anything

So have anyone had any success using that option?

Are you talking about the "Is Marker" flag? Setting that makes the furniture invisible, but it can still be activated by the player.

Huh, I tried this and it wasn't actionable by the player. I think it was a chair that I tried.