Re: Updated DOCTYPE versioning change proposal (ISSUE-4)

Maciej Stachowiak, Sun, 03 Jan 2010 19:45:13 -0800:
>> Documents served as an XML media type MAY include a DOCTYPE header, 
>> either to allow compatible content (so-called “polyglot” documents 
>> which are both valid HTML and also valid XHTML) or to support 
>> version-specific XML processing. While the DOCTYPE header is not 
>> required, including may help in XHTML/HTML crossover.
> Implementations MUST NOT use the DOCTYPE to trigger different 
> processing, but documents MAY use it to support version-specific 
> processing. Why would documents have a need to support 
> version-specific processing if version-specific processing is not 
> allowed?

[Larry often changes subject when he replies, so sorry if I have 
overlooked his answer.]

I think the answer to your question is that one may want to use a DTD 
based validator to check that one has coded a document according to a 
standard. For example, I may define a custom DOCTYPE which picks some 
bits from HTML5. Or use a HTML4 doctype, to which I add some elements 
or attributes from HTML5.

A Web browser should however not be allowed to support version 
specific  processing based on the version and feature info inside the 

But if HTML5 causes more DOCTYPE variants to cause quirks mode, then 
HTML5 has in practices introduced _negative_ version specific 
processing. QuirksMode becomes a punishment for not using the DOCTYPE 
variants that are currently mentioned in HTML5.

See my recent letter:

leif halvard silli

Received on Wednesday, 17 February 2010 03:27:55 UTC