"Pro Web 2.0 Mashups: Remixing Data and Web Services"
0. CHAPTER 4 ?– WORKING WITH FEEDS, RSS, AND ATOM 84 5. Foreign markup is permitted unless explicitly forbidden for specific contexts. See http://tools.ietf.org/ html/rfc4287#section-6 for more details. ?– Note I do not cover RSS 1.0 extensibility here other than to refer readers to RSS 1.0 Modules (http://web.resource.org/rss/1.0/modules/) and to note the standard modules: (http:// web.resource.org/rss/1.0/modules/dc/ (Dublin Core), http://web.resource.org/rss/1.0/ modules/syndication/ (Syndication), and http://web.resource.org/rss/1.0/modules/content/ (Content). Let??™s look at a simple example by adding a tag to the Atom 1.0 feed listed previously. Suppose you want to add a tag called for each of the elements. You can do so by associating the tag with a namespace (say, http://mashupguide.net):6
This example is not meant to show the best way to encode an ISBN but to show how to extend Atom 1.0. Although inserting your own custom vocabulary results in a completely valid document, it doesn??™t necessarily help in terms of interoperability.