You also have solved the mystery why people described it to me as something I could cut and paste if I wanted to use it.

Here is Matt’s response from Sat Jul 2 2005:

Trackback RDF is a highly fragile (and invalid) hack that didn’t work half the time the code was in the page anyway, because most implementations require it to be in the first few K of a page before they stop reading. WordPress/b2 has *never* supported auto-discovery for trackback. We support a *real* non-proprietary standard (pingback) that excels in every way that Trackback fails. (Discovery, spam prevention, internationalization and character set issues, being lightweight, no RDF.) Asking for the RDF back is like asking us to support HTML 3.2 or CDF. When I talked to Ben about Trackback about a year ago he said that the next version of Trackback probably wouldn’t even be compatible with the current and would be based on Atom or something. Finally if people really want to Trackback you they’ll just copy and paste the URL, the WP
dev blog gets hundreds despite never supporting the embedded RDF. If people want it back, the template tag is still there.

WordPress has never supported auto-discovery of TrackBack URLs (i.e. for WP sending trackbacks). The thinking there is that WP supports Pingback which has better autodiscovery and maps more directly to the idea of “A linked B,” whereas TrackBack’s purpose is broader than that. There are circumstances where you might link but not TrackBack, or TrackBack but not link.

WordPress’ bundled themes used to contain the clunky RDF TrackBack autodiscovery block, so MT (and a handful of other tools) could autodiscover the TB URL for a WP post. In March of 2005, Matt axed those autodiscovery blocks. I brought up the issue on the wp-hackers list in July. Here is Matt’s response. I didn’t followup on it, but I probably should have, because that response didn’t really satisfy me. The “first few K” issue is easy to get around: just move the RDF block closer to the start of the document.

This is what I have observed – some themes in WordPress make no mention of TrackBack at all. No big deal IMHO. Other themes though utilize a discovery mechanism that uses a rel=”trackback” attribute on an anchor tag encapsulating the TrackBack endpoint, like this:

Send TrackBacks to

<a rel="trackback" href="http://…/tb.php">http://…/tb.php</a>

I am sure there are other permutations, but I have not really been looking for them.

The proper mechanism is ugly and involves embedding an RDF document inside your HTML like so:

<p>My post content here.</p>
<!–
<rdf>….</rdf>
–>

Ugly – I know. But technically the only valid discovery mechanism.

Regardless of TB’s viability, we really should push to update the protocol as outlined here:

http://www.lifewiki.net/attachments/view/101/2.2

BTW – sorry for not publishing your comment… rectified.

Long before getting involved in WordPress someone explained it to me that those are the reason you see a special URL in Movable Type blogs was so you could copy and paste it and use it to link your article to that article’s comments, and I never questioned it.

Is that what you meant by “the spec is so bad for example that WordPress claims it supports TrackBack, but blatantly doesn’t even implement it as written” in your article? I tried to post a similar question there, but you haven’t published it.

I’ve updated my article.