== All syndication formats use XML

I am pretty sure that [[this http://ai.mee.nu/die_atom_die#c3]] isn't
the first time that I've seen people be grumpy about Atom because it's
an XML-based format. Unfortunately, I have bad news for such people;
to put it one way, it's XML all the way down.

More directly, *all* syndication feed formats, RSS's many variants as
well as Atom, are XML-based (including the versions of RSS that are
based on RDF, since the RDF used is XML-based). This is not just at a
light structural level in RSS's case; you can routinely find RSS feeds
that have _<![CDATA[...]]>_ sections and other significant XML-isms that
cannot just be treated as text (or HTML) inside elements that you 
strip off with a regexp.

Equally, all syndication formats are not XML in real life,
in that attempting to parse any format with a strict XML
parser will not infrequently give you errors (cf [[this comic
http://ansuz.sooke.bc.ca/bonobo-conspiracy/?i=693]]).  This is not even
considering using a validating parser that actually checks the relevant
syndication format specification (you can see how your favorite feeds
would score at [[feedvalidator.org http://feedvalidator.org/]]). In
practice you can produce any syndication feed format with string bashing
and have it consumed, despite errors, by most feed readers.

(Actually, I don't know for sure that Google Reader accepts invalid
syndication feeds. I'd expect it to, but one can never be sure; online
aggregators have been surprisingly picky in the past.)

My overall opinion of the relative merits of Atom and RSS [[remains
unchanged AtomVsRSS]]. However, there's little reason to switch if RSS
meets your needs and doesn't cause problems; feed readers, aggregators,
and so on are going to support both for the indefinite future.