[whatwg] Allow trailing slash in always-empty HTML5 elements?

Elliotte Harold elharo at metalab.unc.edu
Sat Dec 2 08:42:01 PST 2006

Lachlan Hunt wrote:

> HTML 2.0 to 4.01 documents could, in the same way you're insisting on 
> using XML tools on the back end, be reliably parsed using SGML tools. 

Surely you jest. First of all, I believe there was only ever one parser 
that implemented all of the SGML specification, SP from James Clark. In 
practice, SGML documents and parsers were not interoperable. Documents 
and document types were designed to fit the limitations of one specific 

Secondly, anyone who actually tried to use an SGML parser to handle HTML 
  rapidly hit a wall since most HTML documents were not even close to 
actually conformant to the SGML spec or the HTML DTD.

XML, by contrast, learned enough from the experience of SGML to make 
interoperable parsers and documents a reality. It also learned to 
separate well-formedness from validity, which is certainly the single 
most underrated contribution of XML to the field. Well-formedness gives 
80% of the benefit of validity for 20% of the cost. In fact, a lot of 
the time I'd say it gives 120% of the benefit of validity at 20% of the 
cost. Well-formedness sans validity is a large part of extensibility. It 
is what puts the X is XML.

A well-formed XML document is a much lower bar to aim for than a valid 
SGML one.

Elliotte Rusty Harold  elharo at metalab.unc.edu
Java I/O 2nd Edition Just Published!

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