[w3c sml] [4682] Attribute based reference schemes

All
This is an attempt to instigate consensus on this bug. In his excellent writeup on the references, Sandy has proposed that attribute-based reference schemes be supported.  FYI, sml:uri was originally an attribute and it was changed to an element to support extension points. Subsequently, the private SML WG decided to support element-based schemes only for the sake of uniformity.

Please speak up now if you disagree with Sandy's proposal.

Thanks!
Pratul