There is a free text field under the font selection box in Xcode 5. It seems to belong to the Notes category. So: What is the purpose of Notes and the empty bo
The whole "Document" box is just there to help organise your objects in the Storyboard. You can give it a label, so you can easily identify it in the "Scene" list among others.
The Notes, unspectacularly, look like they are just your "notes" about the object, a helper textbox where you can write information that can help you (or someone looking at your project) better understanding what the interface element is for.
Think about it as a "//" comment, but just for visual elements on the Storyboard.