I suspect my ABNF may be a bit wonky, but it's a start and I figured I'd throw this out there and let people comment.
Updated link to C# hal implementation
Added specifications for fragment identifier
Completely forgot about this. Do you use this in your own projects still? I like the idea, I'm just worried it might freak people out if it was in the spec.
I think it might be better to float this some more on the mailing list first and see if it's something people want in the spec or just documented in the client APIs which adopt it. Will close for now if that's ok?
closed with mental note to revisit this once the hal+xml internet draft is being drawn up