[tei-council] soft deprecation of @key: URIs vs. URNs

[Kevin Hawkins]

You'll recall that in Paris we discussed "soft deprecation" of @key, 
whereby we would not actually deprecate this attribute but would add 
prose to the Guidelines telling people they should use @ref instead. 
When we discussed it, we intentionally skipped over implementation 
details since none of us quite remembered the details of URIs vs. URNs 
offhand.

I've done a bit of research in RFCs and Wikipedia and have come up with 
this (see also my comment):

https://sourceforge.net/tracker/index.php?func=detail&aid=3437509&group_id=106328&atid=644065

Regarding my commment, I don't feel confident that I'm recommending the 
right thing.  Who could I call on to help us sort out whether a URI with 
a non-registered Scheme or a URN with a non-registered Namespace 
Identifier is better?  Perhaps a friend of the TEI outside of Council?

Kevin