Rally - What does the Archive field do in Portfolio Items?

Products

• Rally SaaS

Issue/Introduction

In some areas of the product, there is an "Archive" field that can be seen on Portfolio Items.  For example,  on the Portfolio Items page, it is shown in the Field list

However this field does not appear to be exposed in the details page when you view a Portfolio Item.

What is this field for and how do you set it?

Environment

Release:

Component:

Resolution

This field is only exposed on the Portfolio Kanban page

First it needs to be shown as a field on the cards.  

Then, it becomes a modifiable field on a card itself

Once set here, it can be used for filtering purposes