Components like Unity. They're fully networked to client and can add as many as you need.
attribute 'contenteditable' not allowedattribute 'blocktype' not allowed
This is part of making things simpler, like the Tag system last month. If you want to associate some data with an entity, you can add a component now.
attribute 'contenteditable' not allowedattribute 'blocktype' not allowed
As you can see above, there's everything you'd really expect here. There's more work to do but I think this is a good start.