On Feed API, what does the setting "Delete news items older than:" mean? Using FeedAPI on a site I just started working on (but getting ready to get rid of it), and I don't understand this setting:

"Delete news items older than:" 

Does that mean "delete unpublished items after a set time"? Or "delete published items we've turned into posts after a set time"? Or just "ignore items coming in from a given feed if they're older than this?"

Or something else altogether?
This setting does two things:

1) When reading from a feed, ignore items older than this setting.

2) On cron, delete all node feed items older than this setting.