Despite validating with feedvalidator.org and the W3C feed validator, the Firefox XML parser failed on this one feed, as did Sage. Firefox found an undefined entity in the RSS – … – a horizontal ellipsis. I wasn’t sure why that’d break the RSS, so I went digging a little…
RSS doesn’t include an XML schema, which means that a named entity such as … is unlikely to mean anything to a feed reader. … is fine in an XHTML document because it generally has a doctype and a schema.
So if you use data from a content management system to generate RSS, you need to ensure that all named entities are converted into numeric character references.
Numeric character references
As far as I know, numeric character references are generally better supported than named entities. I tend to use numeric character references anyway when I code, as I’m sad and have a bunch of the numbers committed to memory after years of usage – that’s a scary thought!
- horizontal ellipsis (…)
- en dash and em dash (– and —)
- left and right double quote (“ and ”)
- left and right single quote (‘ and ’)
Of course, the real geeks among us will look things up in the full list of character references in the HTML 4 schema!
More useful info at:
- Named versus Numeric Entities
- Atom Compared to RSS 2.0 on Wikipedia
- Numeric character reference on Wikipedia
- Dave, I can’t really afford anything for you off Amazon at the moment, but I certainly owe you a drink or two by now! Back to footnote 1 source