What does [an item described] mean.

I’m reading through the source of Emily Short’s ‘Bronze’, mainly to get an idea of how to format IF.

She’s mentioned something that I don’t quite understand
I was wondering if someone could explain it to me.
http://inform7.com/learn/eg/bronze/source_1.html

It’s in the line The initial appearance of a door is usually "Nearby [an item described] leads [item described direction]."
I’m not sure what [an item described] does.

is it printing the name of the noun currently being referred to?

The item described is essentially a reference to the object itself. Whenever you manipulate properties associated with an object, you can refer back to the object by referring to the item described. That’s not always the noun, and it’s probably better practice to use the item described in this instance (you could imagine what would happen if you printed the text as part of doing something else, or worse, when the current action is nounless).

Whenever you print an object to the screen, it’s converted to text. The specific preposition is used as an easy way of controlling its article. So, the text now produced is something like “Nearby a golden door leads north.” whereas if you’d written the item described, the output would have been “Nearby the golden door leads north.” or something to that effect.

Ahh thanks for clearing that up