Peter Flynn <peter.nosp@m...> scripsit:

>> Is this fragment a valid HTML document ?
>
> Yes, perfectly.

No, it is a valid SGML document, but it is not an HTML document, as defined 
in HTML specifications. (Of course, most "HTML documents" on the Web are not 
HTML documents in that sense, but the question is meaningful only if 
interpreted as relating to specifications. "HTML document" in the loose 
sense - as well as "XML document" when well-formedness is not required - is 
far too fuzzy a concept to be argued about.)

>> If not, why isn't it? Just
>> which part of its definition is forbidding this fragmentary use?
>> <!DOCTYPE div PUBLIC "-//W3C//DTD HTML 4.01//EN"
>> "http://www.w3.org/TR/html4/strict.dtd">
>> <div>
>>     <p>Foo</p>
>> </div>
>
> You can test this by running it through any SGML validating parser
> (eg nsgmls).

That would indicate the validity, but the HTML 4.01 specification requires 
that one of three specific DOCTYPE declarations be used - not just that one 
of three DTDs be used. And this isn't one of them. Moreover, the 
specification explicitly says:
"After document type declaration, the remainder of an HTML document is 
contained by the HTML element."
http://www.w3.org/TR/REC-html40/struct/global.html#h-7.3

-- 
Yucca, http://www.cs.tut.fi/~jkorpela/