I'm currently working on making an RSS feed using PHP. I plan on having it served as application/rss+xml as it should be. But if a browser tries to view it and doesn't have any support or plugin for RSS, I'd like to echo an XSL transformation. I've only tried a few stand-alone RSS readers (rather than browser plugins) and I'm wondering if it's normal for these readers to not have an HTTP header with their request. Would that be a fair assumption? They seem to ignore XSL transformation, but I don't want any conflicts in rendering.