As I mentioned yesterday, there will be three types of challenges facing any effort to merge RSS and Atom: technical issues, goals, and personalities. Personality issues need no comment here.

Technical: a few technical questions that will need to be resolved include:

• Will the format have a namespace, or will it just have the ability (as now) to be extended using namespaces? The Atom folks are likely to want a namespace. The RSS 2.0 folks may prefer not to have one for backwards compatibility.

• What will the elements be named? There are a number of elements in each format with equivalent purposes. I would assume that for those (rss vs. feed, item vs. entry, etc.) the RSS names will prevail.

• Where the two formats each have elements with the same purpose, but a different format, which will be supported? The RSS elements? The Atom elements? Whichever is technically superior? Or both?

Goals: Both RSS and Atom are primarily focused on blogging, though they are also used for various other purposes. This fact should help in any effort to reconcile the two. But the goals of the people behind each format are mismatched in other ways. Perhaps the most problematic will be Dave Winer's goal of backwards compatibility--a point on which he seems unlikely to bend significantly--versus the Atom camp's willingness to drop backwards compatibility to create a technically superior format.

Although the goal of simplifying decisions for developers, and expanding options for consumers, by having a single format is noble, I have a difficult time imagining RSS and Atom coming together. Nor do I expect that the resulting standard would be what we want. In this case, it's probably better to continue development along both lines, and let the market decide whether to settle on one, the other, or most likely, on both.