The choice of syntax for global identifiers is somewhat arbitrary; it is their global scope that is important. The Uniform Resource Identifier, [URI], has been successfully deployed since the creation of the Web. There are substantial benefits to participating in the existing network of URIs, including linking, bookmarking, caching, and indexing by search engines, and there are substantial costs to creating a new identification system that has the same properties as URIs.
A resource should have an associated URI if another party might reasonably want to create a hypertext link to it, make or refute assertions about it, retrieve or cache a representation of it, include all or part of it by reference into another representation, annotate it, or perform other operations on it. Software developers should expect that sharing URIs across applications will be useful, even if that utility is not initially evident.
There is so much packed into each of these brief statements, and they are in equivalent of the first 10 pages of the document.
I find it both amazing and sad that this document was published in 2004 yet I've found very few references to it in the six years since it's publication. Maybe I just haven't been looking in the right places?
I will share additional passages that I find enlightening in the days (and weeks?) to come.