It seems that Dare Obasanjo thinks there are two ways to support podcasts in Atom and one in RSS2.0. He's incorrect in his analysis, which goes as follows: Atom for podcasts - use an atom:link whose @rel type is 'enclosure' to link to an audio file. Or use an atom:content whose type attribute is audio/mpeg (or some such media type value) and which links to an audio file. RSS2.0 for podcasts - use rss2:enclosure whose type attribute is audio/mpeg (or some such media type value) and which links to an audio file. But, RSS2.0 also allows you to link to an audio with rss2:link element. That would be similar in spirit to the atom:content way of doing it, insofar as it's not the spirit of either spec to link to audio files for the purposes, else neither would offer syntax for enclosures. As we're navel-gazing on the specs here rather than looking at what anyone actually does, the only interesting difference for podcasting is the fact that atom:link and atom:content both allow media type declarations as metadata. Whereas only rss2:enclosure allows the media type to be set and the rss2:link with its absence will defer to the media type set in the HTTP response. Some of this also comes down to conflating "podcasting" with "enclosures" with "links", which though it makes sense conversational to avoid pendantry, in the way "AJAX" and "Web2.0" makes broad conversational sense, it is wooly thinking technically. Conclusions: Atom and RSS2.0 don't support "podcasting". Technically speaking, "podcasting" is about as meaningful here as "Web2.0" or "AJAX". Atom and RSS2.0 support the notion of an enclosure, which is the basis for most "podcasting" functionality. Mixing up enclosures and podcasting is a mistake. Atom and RSS2.0 have the notion of a link, which could be used to support linking to audio and other non-textual media. Mixing up enclosures and linking is a mistake. To add some flavour, Apple has published a spec for enabling podcasting via RSS2.0. It's specifically targeted at the iTunes application, and can be described as an RSS2.0 extension for that purpose. As an extension it could be supported by any software that supported RSS2.0. I think it would be weasel-worded to describe this as a 2nd (or even 3rd) way for RSS2.0 to support podcasting, even though it is more closely aligned with that kind of functionality than an rss2:link. It's more of an application-specific extension for iTunes. Intereatingly, there is of course nothing to stop this iTunes extension being published via Atom or any other syndication format, making it a kind of feed-agnostic vendor-specific microprotocol. I personally expect to see more of these as a function of the markets enabled by more generic innovations, such as enclosures....
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