Preview is a wonderful thing. Phillip?
But I have to disagree with Georg that preview solves everything for RSS. For the most basic case, single-encoded angle brackets in description, it probably mostly does: I can find some things that read RSS but don't treat the Reuter's stock symbols as HTML tags, but it will take some looking, and it would be pretty obvious that they are old and broken in other ways. But once you start looking at more elaborate things, and things like treatment of entities in title, or HTML in channel/description, you need to have a Windows machine, a Mac, and Linux, with dozens of aggregators installed on each one, just to find out what you can and can't do. And I need to, too. And so does Sam, and Georg, and Randy, and Ian, and everyone else who ever wants to do anything other than plain text, just like the way we did HTML during the browser wars.
The aggregators work just fine? When I first learned about this problem, 18 months or so ago, it took me four different aggregators to find one that would let me read one of Sam's posts.
And while we claim that everybody knows how to deal with RSS 2.0 and HTML, what about RSS 0.91? It still exists, and every aggregator claims to be able to read it. Do any aggregators at all correctly read it, treating a once-encoded less-than as something which should display as a literal less-than, not be treated as the start of an HTML tag? There is no HTML in RSS 0.91, and the spec makes it clear that if you want to say that 1 is less than 2, you encode the less-than symbol *once*. Sure, forgiving browsers will usually display that, but what about 1 is less than 5 is greater than 4?