RSS <pubDate> tag
Usage
Specifies the publication date for an RSS feed/item. If the publication date is in the future, then feed readers may choose to not display the feed/item until that date.
Example
RSS feed with pubDate:
<?xml version="1.0" encoding="ISO-8859-1" ?>
<rss version="2.0">
<channel>
<title>Landofcode.com web tutorials updates</title>
<link>http://www.landofcode.com</link>
<description>Web development tutorials</description>
<pubDate>Wed, 10 March 2008</pubDate>
<item>
<title>Site usability</title>
<link>http://www.landofcode.com/usability.html</link>
<description>Learn how to improve the usability of your site</description>
<pubDate>Wed, 10 March 2008</pubDate>
</item>
<item>
<title>New HTML tutorials</title>
<link>http://www.landofcode.com/html-tutorials/</link>
<description>Five new HTML tutorials have been added</description>
<pubDate>Thu, 11 March 2008</pubDate>
</item>
</channel>
</rss>