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

Michel Fortin michel.fortin at michelf.com
Sat Dec 2 04:18:02 PST 2006

Le 1 déc. 2006 à 17:45, Ian Hickson a écrit :
> You don't need to do one or the other. It's just up to you which  
> you do.
> Neither is better or worse than the other. They are equivalent,  
> neither is
> deprecated, they are both unambiguous, they are both strict, they will
> both have validators and they will both have tools that can be used to
> process them. There's no reason to try and do both.

I disagree with this choice-of-tool argument.

If you develop software to be used by other people, or other  
programs, you don't want to lock them in either camp, so you have to  
provide a way to generate both outputs. That's especially important  
when programs and libraries are exchanging documents or snippets of  
documents between each other. The DOM is a poor choice for these  
exchanges, because different DOM implementation are not interoperable  
between each other. The markup on the other hand can move more freely.

Having two markups pose the same problem as having two incompatible  
HD DVD formats. Browsers do (or will) accept both formats, so as long  
as the media type is known it'll work fine for them. But what about  
every other piece of software in the middle that does not talk  
directly to the browser?

That's the real difficulty when dealing with HTML and XHTML: the  
choice isn't really about tools, it's a choice between two  
incompatible exchange format. That's the reason why I think it's  
compelling to have a common subset between HTML and XHTML. If you can  
output something valid for both HTML and XHTML at the same time, then  
you don't have to worry about what format is supported on the other end.

That's also why it's probably worth knowing what the common subset  
looks like, how people might be tempted to use it, and what are its  
exact limitations and pitfalls. The common subset is an integral part  
of the the HTML/XHTML couple; it may be just a side effect, but it's  
there and should not be ignored. It's pretty clear to me that it'll  
be used whether we want it or not.

Oh, and here is one last remark. There are really *two* important  
common subsets: one between conformant HTML and conformant XHTML, and  
another between unambiguous HTML and well-formed XHTML. The first was  
pretty irrelevant before HTML allowed "/>", but it did not prevent  
people from using the second.

Michel Fortin
michel.fortin at michelf.com

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