Re: Polyglot Markup/XML encoding declaration

On Sun, Aug 1, 2010 at 5:05 PM, Maciej Stachowiak <mjs@apple.com> wrote:
>
> (chair hat off)
>
> On Aug 1, 2010, at 12:55 AM, Leif Halvard Silli wrote:
>
>> Lachlan Hunt, Thu, 29 Jul 2010 15:30:02 +0200:
>>>
>>> A polyglot may be served as HTML too.  HTML5 does consider the XML
>>> declaration to be non-conformant, and including it is unnecessary
>>> polution.
>>
>> This touches the question of whether Polyglot Markup is a specification
>> or a authoring guide. The TAG by Tim Berners Lee has suggested that is
>> to be a specification. Of course, even as a spec, it does not need to
>> include the xml declaration. But if it is a spec, then it could include
>> it.
>
> [...]
>
>>>> The XML declaration would not be generally permitted in HTML - it would
>>>> only be permitted in polyglot markup.
>>>
>>> There is no way to make some syntax conforming for polyglot documents
>>> only.
>>
>> Just make a validator which does.
>
> The original premise of the polyglot spec was to describe a type of document that is valid as both HTML5 and XHTML5, and works sufficiently the same both ways. Thus, it does not match the original goals to have a construct that is valid in polyglot documents, but invalid in at least one of HTML5 or XHTML5. Indeed, Lachlan already pointed this out:
>
>>
>>> Such a requirement is unenforceable because the conforming
>>> polyglot document syntax is and should remain only the intersection
>>> of HTML and XHTML syntax.

I concur with Lachlan and Maciej.


> Also, besides this general point, there is the fact that an XML declaration will trigger quirks mode in some legacy UAs, thus it is a bad idea to serve content including an XML declaration as text/html.

Indeed, I was a bit shocked to even see the XML declaration suggested
for polyglot documents - as the XML decl = quirks mode is well known
by professional web authors/designers/developers.

Additionally I think it is necessary to adopt a principle of
minimalism for any recommendation for polyglot documents.

I have found in practice that when teaching workshops / speaking etc.
about HTML5 that there are still plenty of people who either want to
maintain some semblance of XHTML/XML compatibility, or are required
to, and from their perspective, the *simpler* it is to do so, the
better.

The *fewer* things they have to remember or worry about, the better.

Thus not only should we reject the XML declaration in particular, but
we should categorically reject adding *anything* into the suggested
markup patterns that isn't absolutely essential for polyglot documents
to function as expected / similarly.

The burden of proof must be on those who want to recommend additional
markup/code, to demonstrate how omitting such markup would cause a
problem with real world (X)HTML5 documents.  Otherwise we shouldn't
even bother to consider it.

Plenty of folks are able to publish biglot/polyglot (X)HTML5 documents
*today* without the XML declaration, thus we should have rejected the
suggestion immediately.

Thanks,

Tantek

-- 
http://tantek.com/ - I made an HTML5 tutorial! http://tantek.com/html5

Received on Monday, 2 August 2010 00:41:57 UTC