RE: url versus urn for namespace uri?

> 1) Are there any pros and cons for using a URN for a 
> namespace URI?  It seems that most people use URLs but I feel 
> like that adds to the confusion with people expecting that 
> URL to have something there if you go to it with a web browser.

Some people like to use a namespace URI that can be dereferenced to locate a
"namespace document" of some kind. This is standard practice in W3C, for
example.

In my mind this represents a gross confusion: a URI should uniquely identify
a single thing, and using the same URI to identify a namespace as well as a
document containing a human-readable or machine-readable description of the
namespace is a cheat. It's confusing the thing with a document describing
the thing. But it's an established convention, so who am I to argue?

The rot of using URIs starting with "http" set in a long time ago, and it's
probably best to just swim with the tide.

Regards,

Michael Kay
http://www.saxonica.com/
http://twitter.com/michaelhkay