RSS Item Element Usage Stats
In RSS Profile research, I analyzed how frequently RSS core elements and namespace elements appear in feeds.
Here's the compiled stats for item elements. Part one covered channel element usage.
The full report reveals that the most popular namespace element in RSS items is dc:creator from the Dublin Core namespace, which appeared in 42.7 percent of the feeds.
The second-most common is wfw:commentRss from the Well-Formed Web namespace, appearing in 34.3 percent. (This total includes wfw:commentRSS, a common miscapitalization of the element name.)
All core elements were found in at least 5 percent of the feeds surveyed with the exception of source, which appeared in 3.0 percent.
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RSS Channel Element Usage Stats
As part of the research for the RSS Profile, I compiled statistics on how frequently RSS core elements and namespace elements appear in feeds.
The full report reveals that the most popular namespace element is dc:language from the Dublin Core namespace, which appeared in 36 percent of the feeds.
The second-most common namespace element is atom:link from the Atom syndication format, appearing in 15 percent.
Four core elements were found in fewer than 1 percent of the feeds surveyed: textInput (0.31 percent), rating (0.26), skipDays (0.10) and the skipDays element day (also 0.10).
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Proposal: Spec Clarification on Namespaces
The following RSS Advisory Board proposal has been made by Randy Charles Morin and seconded by Rogers Cadenhead.
Under the advisory board charter, the board has seven days to discuss the proposal followed by seven days to vote on it. Interested parties can comment on the proposal on the mailing list RSS-Public.
Proposal
We'd like to propose a small clarification to the RSS 2.0 specification to remove uncertainty in the community over whether extension attributes are allowed to core RSS elements.
In the section Extending RSS, we propose that the following sentence be changed:
A RSS feed may contain elements not described on this page, only if those elements are defined in a namespace.
It should be revised to read as follows:
A RSS feed may contain elements and attributes not described on this page, only if those elements and attributes are defined in a namespace.
Rationale
When namespaces were added to RSS 2.0 by Dave Winer in 2002, he wrote on his weblog that he was deferring the details of their implementation to the Namespaces in XML specification:
I've added the section explaining how to extend RSS through namespaces. I'm basically telling you to ask the W3C how namespaces work, and do it the way they tell you to do it. I don't want to assume the problem of documenting namespaces in the RSS spec.
When namespace support was added, that version of the specification linked to a new RSS 2.0 sample file that used them. This sample file was part of the specification for the next two years.
The first line in the sample file makes use of a namespace attribute:
<rss version="2.0"
xmlns:blogChannel="http://backend.userland.com/blogChannelModule">
In the above, xmlns:blogChannel is a namespace attribute contained by the rss element that declares the blogChannel namespace.
The proposed spec revision makes it clear that this is valid RSS. If namespace attributes aren't valid RSS, every RSS feed that declares a namespace in the rss element is invalid.
Some namespace developers, most notably Microsoft, have employed namespace attributes on core elements.
To clear up confusion, support implementers who've emulated the specification, and give more clear guidance to namespace creators, this is an important and necessary clarification.
Video: RSS in Plain English
If you're interested in RSS but you don't know where to start learning about it, Lee and Sachi LeFever of The Common Craft Show have created RSS in Plain English, a breezy video that explains it in under four minutes.
Linking to the RSS 2.0 Specification
As chairman of the RSS Advisory Board, I've been called into two discussions recently about where people should link when referring to RSS 2.0.
There are two leading contenders: the RSS 2.0 specification published by the board and an older copy archived by Dave Winer.
The board's web site moved off Harvard's server in January 2006 to our own domain, rssboard.org. We've published the RSS 2.0 specification since 2003 and the current version of the document will always have the permanent URL http://www.rssboard.org/rss-specification. Our transition from Harvard's server to our own was described here.
Contrary to some claims I've read, the specification does not include new RSS elements or attributes that differ from what the board published prior to the server move. The only changes we've made to the document were administrative ones described in an August 2006 proposal and vote.
We're a public group that operates under a charter and has members from Microsoft, Yahoo, Netscape, Six Apart, BlogLines and others in the RSS community. I was asked to join in 2004 by Winer, who resigned shortly thereafter. I recently began a new two-year term as chair.
The copy of the RSS 2.0 specification archived by Winer is a just an older version of the spec. The board has archived the same version along with all of the older specs, for historical purposes.
There's contention within the RSS community about our work, as there is with anything involving RSS and syndication. But we've been conservative in regard to the specification and all other matters related to the format. We're primarily a place where people can get help with the format and developers can promote new namespaces and other ways to improve interoperability. Anyone who has questions about what we do is invited to join us on the public mailing list RSS-Public.
