[html5] html 5 dtd

Ian Hickson ian at hixie.ch
Tue Mar 10 12:30:01 PDT 2009

On Tue, 10 Mar 2009, Stephen Caine wrote:
> We are revising an application that uses a dtd for validating and 
> controlling a web form.  Specifically, a user is presented with a list 
> of available tags, each tag is then shown with allowable attributes 
> which are checked for the correct type of entry.  We also eliminate the 
> need for a user to enter closing tags by using a parent/child outline 
> layout.  This works great, but thinking about html 5, we are concerned 
> in that no dtd is envisioned.  What alternatives exists or are 
> contemplated for an html 5 dtd?

No formal DTD exists, but you can create your own custom DTD for your 

> I would also like to know why an html 5 dtd cannot be created?  After 
> reading the specification, it appears that html 5 will contain tags and 
> attributes. Furthermore, it appears that opening/closing tags are still 
> part of the specification.  Can't the html 4 dtd be modified to 
> accommodate html 5?

There's no official formal schema for HTML5 because we have found that 
providing an official formal schema leads to people using that schema even 
if it is buggy, never considering writing their own. By not having an 
official formal schema, we have found that implementors are more likely to 
write their own code, competing on quality.

Basically, a schema is code, just like a C++ implementation of the parsing 
model would be code, and just as it is unusual for a spec to have C++ 
code, it should (IMHO) be unusual for a spec to have formal schemas.

However, you are welcome to create your own formal schema implementations 
of HTML5.

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'

More information about the Help mailing list