TB16 Re: Comments on arch doc draft

> In point of fact since a URI reference optionally is relative and 
> optionally has a fragment identifier, there are naturally four classes 
> of things here.  I think we should name them, define them, and make it 
> handy for other people to use them.   Strawman language:
> 
> "A URI reference contains a URI, which may be relative or absolute, and 
> optionally has a trailing #-delimited fragment identifier.  Thus there 
> are four classes of identifier, all of which are URI References:
> 
> 1. URI - not relative, no fragment.  This is what is sent from an agent 
> to another in the dereferencing process.
> 2. Fragment-free URI Reference - relative allowed, no fragment.  As an 
> example, XML 1.0 requires SYSTEM identifiers to be of this class.
> 3. Absolute URI Reference - relative disallowed, fragment allowed.  In 
> practice, almost all XML namespace names are of this class.
> 4. Unrestricted URI Reference
> 
> W3C Recommendations MUST be clear as to which class of identifiers they 
> support."

I think we should establish at the strong SHOULD level that
relative URIs should/must be allowed in a syntax wherever 
absolute ones are.

The only example I can think of where they are not
allowed (xmlns) was shown to be a problem at our Hawaii
tag face-face, when most of the GET URI for a query was
a namespace URI which could have been dramatically
shortened if made relative to the URI of the query itself!

timbl