Re: Tags inside themselves??

"Daniel W. Connolly" <connolly@hal.com>
Date: Mon, 12 Sep 94 01:15:07 EDT
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From: "Daniel W. Connolly" <connolly@hal.com>
To: Multiple recipients of list <html-wg@oclc.org>
Subject: Re: Tags inside themselves?? 
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In message <199409102330.AA02904@char.vnet.net>, Stan Newton writes:
>The following message body is a retransmission of an earlier message to
>www-html@info.cern.ch, from which I received no reply:

By the way... I suspect an administrative problem. I subscribe to
www-html, and I think I would have rememberd seeing comments like
this if they had made it to my mailbox.

>------------------------------------------------------------------------
>
>The HTML DTD Reference (Level 2) states that BLOCKQUOTE tags are allowed in 
>BLOCKQUOTE tags (pg 6-2) but nesting of BLOCKQUOTEs and possible rendering 
>is not discussed. The HTML DTD (pg 5-5 & 5-7) defines BLOCKQUOTE as a member 
>of the %block Entity and defines the BLOCKQUOTE Element to contain 
>%body.content which includes %block. Is this intentional? Can I have 
>Blockquotes inside Blockquotes, that is, can Blockquotes be nested?

Dave Raggett also asked about this...

At the time I drafted the DTD, I got this idea that it would be neat
to be able to select a range of text in one browser, and paste it into
an editor, which would mark it up like:

	<BLOCKQUOTE>
		...selected text...
	<address>author/url of selected text</address>
	<BLOCKQUOTE>

If blockquotes aren't allowed inside blockquotes, this is not possible
in general.

My little fantasies aside, Mosaic (nor any other browser I know) does
not distinguish nested blockquotes from non-nested blockquotes. So
perhaps blockquote-inside-blockquote should be postponed to a later
version of the spec.

>The HTML DTD Reference (Level 2) states for each of the Highlighting tags 
>(B, CITE, etc.) that the tags are allowed inside of themselves. See, for 
>example, Bold (pg 6-2). The HTML Level 1 DTD (pg 5-10) defines allowable 
>content for %font and %phrase elements in terms of a %phrase.content entity 
>definition which includes the %font and %phrase entity definitions, thereby 
>placing the tags inside themselves.
>
>Shouldn't each of the Highlighting tags be allowed to include all 
>Highlighting tags EXCEPT ITSELF? Since the Highlighting for any specific tag 
>should already be on, the appearance of another tag with the same 
>Highlighting does nothing and has the potential to confuse some 
>viewers/processors.

The issue of nested Highlighting elements was discussed in Toronto.
I'm not sure if anybody wrote up the results anywhere...

I believe the consensus was that nested highlighting markup was
not an error, but a browser was not required to distinguish
nested markup from non-nested markup. i.e. a conforming implementation
may render the following two cases identically:

	<i>italic with <b>bold</b></i>
	<i>italic with </i><b>bold</b>

Not that it's necessarily relevant, but as an example, in TeX markup,
it is quite common to see {\em title with nested {\em emphasis}}.
It is also conforming to render:

	<em>title with nested <em>emphasis</em></em>
just like:
	<i>title with nested </i>emphasis
(hmmm... there's no "plain" or "roman" tag!?!?)

Dan