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Re: Relationship types





Len Bullard <cbullard@hiwaay.net> wrote:
> Jon Bosak wrote:
> > [Len Bullard:]
> > | >    PREVIOUS
> > | goto
> >
> > No.  "goto" says "do something with regard to this link end."
> > "PREVIOUS" says "know something with regard to this link end."
>
> previous = goto().  That is why those JavaScript function calls
> are in HTML.


Midas, an early Motif-based Web browser, took an interesting
approach for its "history list".  Instead of the conventional
LIFO stack (where selecting a link pushes the current document
and the "Back" button pops the last one), it built a "history
tree" by intuiting a hierarchical structure from the links
in each visited document.  (I think the latest version of NCSA
Mosaic for X, alas forever in beta, has a similar feature.)

It worked pretty well, especially for Web collections that
were in fact hierarchical in nature.  After browsing a typical
LaTeX2HTML-generated document, the history tree tended
to evolve into a fairly good hierarchical, collapsible table
of contents.  

There were flaws, of course; the process was purely heuristic
and was sensitive to the initial browsing order (it couldn't
distinguish between "next section", "first subsection", and
"cross-reference to a completely different chapter" links, for
example), but I couldn't help thinking that if more authors and
HTML generators took advantage of the "REL" attribute, the Midas
history tree would have made a powerful navigation aid.

To sum up:  no, "previous" is *not* equal to "goto", regardless of 
whether Netscape and JavaScript implement it that way.


--Joe English

  jenglish@crl.com


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