Re: Simplicity of core versioning support

User's determine resource identifiers (URLs) and servers map these names 
to physical resources. When we add versioning, we need to include a 
composite identifier to distinguish between multiple revisions of the same 
versioned resource. Labels allow a user to define such an identifier in 
some way that is meaningful to them. Again it should be the server's 
responsibility to map this to a particular version. Having servers provide 
visible, server generated, immutable resource (i.e., object) identifiers 
is necessary too. We can do all sorts of linking with these identifiers 
that would be impossible using user specified identifiers that can change 
through BIND and LABEL. Since core versioning introduces versions of 
resources, I think it needs to provide a way for users to identify them. 
This is just a logical extension of the server's role for identifying 
unversioned resources. So I think LABEL belongs in core versioning. A 
server can always implement it by refusing the label. This would be a 
somewhat constrained server, but it might have other interesting 
characteristics.