What is the purpose of 'Notes' under Document in XCode

Question

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 box under No Font shown in the image below?

Answer 1

I have tried to use notes for one of my component i.e a button for me and added some notes for it as in the image 1.

Here is the xml file for the button in XIB ,where you can see it is a comment used for user reference.