P4 to P5

[Syd Bauman]

> I now imagine
>   <TEI xmlns="http://namespace.tei-c.org/" teiversion="5">
> how does that strike others?

I'd still like to know if it makes sense to use a URN instead of a
URL, and if not, why not.

The version number is too imprecise. Although we prefer to avoid
doing it, we do make real changes between major releases. I'm in
favor of something along the lines of "P4:2002-05".