Update 10 August 2012: in response to a query, I checked again and pubdate is gone from both the WHATWG and W3C specs.
Previously, you could only mark up precise dates. So, 13 November 1905 could be expressed in HTML <time datetime="1905-11-13"> but November 1905 couldn’t be. This is a problem for historians where sometimes the precise date isn’t known.
Neither can you indicate date ranges. To mark up From “21/02/2012 to 25/02/2012″, use two separate <time> elements.
