Re: 4.b Links pointing at links?

Tim Bray wrote:
> At 12:33 PM 3/4/97 -0800, Tim Bray wrote:
> >4.b What should we say about the situation when a linking element points
> >at a resource which is another linking element?
> Tough one.  I see three choices:
>  1. duck, say nothing
>  2. say we indirect one level, as Durand proposes
>  3. make this another axis of behavior policy specification, a
>     numeric-valued attribute, i.e. INDIRECT-CEILING=4?
>  4. say we never indirect, leaving it up to the application.  I think we're
>     going to get enough of TEI XPTR to have most of the goodness of
>     location ladders.
> I go for #4. -T.

1.  Can't do that.  Location ladder concepts are showing up in
other languages.  Mark Pesce has this as the cornerstone of 
his CyberProtocol speech although he does not acknowledge the 
concept predates his papers.  Indirection of this kind is 
far too common in even human speech to avoid it.

2.  If that means, indirect to, which can, indirect to, fine.
A rung in a ladder only has two neighbors with the exceptions 
of the ends.  Why would only one level of indirection be 
more useful than none?

3.  Kind of baroque.  It won't prevent circularity, and it 
doesn't give us anything that we need.  I think this is like the 
"let the links snap" decision made for URLs.  If they point 
to a link to a link to the deep blue ocean, that is something 
they should find when they test the links.  If they don't test 
their links, someone will.  If no one does, it doesn't matter.

4.  Same as one.  

I'll have to go back and look at TEI XPTR again to see.  As I 
recall, location ladders are useful when the linkages have 
to mix types of locators in order to identify a resource.  In a 
sense, that mixes the link with the scheme.  Is that what we 
give up here?