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Re: XHTML

From: Chris Maden <crism@oreilly.com>
Date: Tue, 3 Aug 1999 13:51:54 -0400 (EDT)
Message-Id: <199908031751.NAA16832@ruby.ora.com>
To: www-html@w3.org
[Alex Blewitt]
> I do not particularly like the style of checked="checked" for input
> types.  It seems a little bit of overkill to have the repetition of
> 'checked' in the HTML source.

The reason for this is so that you can enter <input checked>.

In SGML, when there's a list of allowable tokens for an attribute
value:

<!ATTLIST element
          attribute (val1 | val2) #IMPLIED>

you can just enter the value: <element val1> and the name of the
attribute can be inferred.

Because of that minimization rule, it was illegal to have multiple
attributes with overlapping token values:

<!ATTLIST ILLEGALELEMENT
          attribute1 (val1 | val2) #IMPLIED
          attribute2 (val2 | val3) #IMPLIED>

So it was common practice with Boolean attributes to have an attribute
whose legal values were the name of the attribute, or nothing at all:

<!ATTLIST element-with-booleans
          boolean1 (boolean1) #IMPLIED
          boolean2 (boolean2) #IMPLIED>

That way, you could just invoke the Boolean by name:
<element-with-booleans boolean1> has boolean1 true and boolean2 false.

XML has made both attribute names and values required, so this
minimization is irrelevant; additionally, WebSGML has relaxed the
restriction on overlapping token values, as long as document instances
aren't ambiguous.

In light of those changes, a change for XHTML like you suggest might
make sense, but it would mean that converting from HTML to XHTML was
no longer a simple matter of normalization (with a tool like SX), but
would require more heuristics, knowing that checked="checked" was
equivalent to checked="yes".  Maybe multiple values could be allowed:

<!ATTLIST input
          checked (checked | yes | no) "no">

-Chris
-- 
<!NOTATION SGML.Geek PUBLIC "-//Anonymous//NOTATION SGML Geek//EN">
<!ENTITY crism PUBLIC "-//O'Reilly//NONSGML Christopher R. Maden//EN"
"<URL>http://www.oreilly.com/people/staff/crism/ <TEL>+1.617.499.7487
<USMAIL>90 Sherman Street, Cambridge, MA 02140 USA" NDATA SGML.Geek>
Received on Tuesday, 3 August 1999 13:52:26 GMT

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