[wp-xmlrpc] Versioning the WP API post attribute extensions

[Daniel Jalkut]

I'd like to call list members' attention to a trac issue I opened:

http://trac.wordpress.org/ticket/4590

The gist is that we need some way to tell programatically whether a  
server supports particular attributes on posts. For instance, WP has  
added the "wp_slug" attribute to posts, but as of today, the only way  
to know that it will be excepted is by assuming that the presence of a  
"WordPress" API in the RSD for a site, implies that the "WP"  
extensions to MovableType are all supported.

I'd like to see something akin to the "supportedMethods" call  
implemented in a way that allows us to check for  
"supportedAttributes." But I haven't thought it out too well. I'm just  
putting it into Trac to get it out there. What do you all think?

Daniel