Re: The value of navigability

Bert Bos <>
Date: Tue, 7 Jun 1994 18:38:18 +0200
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From: Bert Bos <>
To: Multiple recipients of list <>
Subject: Re: The value of navigability
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Dave Raggett writes:

 |Gavin Nicol writes:
 |> ... parts of a document can be formatted to best help people understand
 |> the information. Such formatting might include removing large parts of
 |> irrelevant data (for example, if you had a play, you might remove
 |> everything *except* the names of the speakers, and when you clicked on
 |> the speaker name, a box containing the speakers lines might appear).
 |I think we ought to bite the bullet and support SGML's marked sections.
 |This allow you to switch on/off sections of a document with simple entity
 |declarations that can be set in the <!DOCTYPE> declaration or set by
 |client-side scripts or user preferences. It is too late to do this for
 |HTML 2.0, but I see no reason why HTML 3.0 compliant browsers should
 |duck this issue. The parsing mechanism is quite easy to implement.

Marked sections are very convenient for authors, and I agree that they
are not very difficult to implement. But I have some trouble imagining
the user interface at the client side. Should the browser present the
user with a message box saying:

	| This doc has multiple levels.   |
	| Check the ones you want to see. |
	|                                 |
	|  O  STGDIR                      |
	|  O  SPEECH                      |
	|  O  MRGNNUM                     |
	|                                 |
	|           +----------+          |
	|           |    OK    |          |
	|           +----------+          |
	+---------------------------------+ ?

How will the user know what the entities mean, by trial and error? One
method is to prescribe the entities and their meaning, but then we're
back at the problem of choosing semantic primitives. When you say
`user preferences' you seem to assume something like this.

The client-side scripts could indeed provide a solutions, since they
would allow the author of the document to, in fact, program this
dialog box himself.

BTW. this is different from the `folding elements' that were discussed
earlier. The folding element would have a button in the text that
indicated a hidden text. With marked sections, there is no indication
in the text at all.

                    / _   Bert Bos <>   |
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