Correct/Accepted Way to Update an ATOM Entry

[nalyque]

What's to "correct" way to indicate an entry in an ATOM feed is updated?By "correct" I mean fits into existing specifications and something feed readers will notice and mark as new/unread.All the specifications I've found say there's support for an updated node. However, when I try something like this\[code\]<entry> <title>Ipv4 For Sale</title> <link href="http://tech.slashdot.org/story/12/05/24/1526258/sales-of-unused-ipv4-addresses-gaining-steam"/> <id>urn:uuid:0fd0a227-1be0-bce4-9f53-8c47bf682eb7</id> <updated>2012-05-24T15:18:19-07:00</updated> <published>2012-05-24T13:11:37-07:00</published> <summary type="html"><![CDATA[<p>Web Content Here</p>]]></summary></entry>\[/code\]my feed reader will display the new content, but it will NOT mark the item as new/unread. I'm using NetNewsWire which is both a mainstream feed reader, and has a setting to "Mark as Unread" any "Updated" items. There's a few other Stack Overflow questions on this subject, and while the ones I read confirm the behavior I've described above, none (seem to?) provide a solution.Is there a way to do this, or is the "correct" thing to post a completely new entry?Using PHP's DATE_ATOM constant to generate the feed dates, if that matters.