Bert Bos <>
Message-id: <>
From: Bert Bos <>
Subject: Re: PATHs in HTML
To: (* WWW discussion list )
Date: Wed, 12 Jan 1994 19:56:13 +0100 (MET)
In-Reply-To: <m0pK9k0-00005lC@monolith> from "William M. Perry" at Jan 12, 94 12:52:00 pm
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Bill Perry asks:

 |  Now what exactly is the format of something pointed to by
 |REL=Subdocument?  Just a list of URLs like:
 |   Or just a bunch of <LINK > attributes?  Would the REL attributes still
 |all be Subdocument?  Would there be a NAME attribute?
 |<LINK REL=Subdocument NAME="My weird path around IU">

No, the beauty of the scheme is that there is nothing in the target
document that makes it into a node of a path. The document that
contains the rel=Subdocument itself *is* the path. As an example, here
is a valid path. Note that it is a perfectly normal HTML document.

  <!doctype html>
  <title>My path around Mosaic</title>
  <h1>My path around Mosaic</h1>
  You should read the following in this order:
  <li><a rel=subdocument href=
  "">Mosaic demo</a>
  <li><a rel=subdocument href= 
  "">About HTML</a>
  <li><a rel=subdocument href=
  "">About URLs</a>

This would be a document on my server, but it builds a path out of
nodes that are read-only to me. A browser that displays the above text
would note the occurrence of three Subdocuments and offer to the user
to display all three of them one after the other (the "Traverse
current path" button).

When the user decides to "traverse the path", the first subdocument
("Mosaic demo") is retrieved and displayed normally. The user can do
anything he normally does, but in addition he can now also press the
spacebar and be transported to the second document ("About HTML"). The
next press of the spacebar would retrieve the third node ("About
URLs") and the fourth would be an error.

Another way to view this is to imagine that the browser "queues" all
links that have rel=Subdocument. When the user doesn't select a link
explicitly, the next node from the queue is popped and displayed

NB1: the "spacebar" is just an example, it could be any other key or
mouse click. 

NB2: the "queue" model is inaccurate, in the following way: when
you're already traversing a path, occurences of Subdocument are not
queued, but occurrences of Path are.

NB3: The above is just my interpretation. Jim McBeath or Dave Raggett
can probably do better.

                    / _   Bert Bos <>  |
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