[html5] Identifying HTML 5 documents? (vs. alternate flavors)

[Jim Correia]

[I prematurely hit send on the last message. This message augments the  
last.]

On Feb 8, 2008, at 4:44 AM, Henri Sivonen wrote:

> If there are issues we don't foresee now but we see when the  
> successor of HTML5 is being defined, we can make the successor have  
> a distinguishing feature at that time.

After reading through the message you pointed through, as well as  
others found via searching, it sounds as though we've been around this  
block a time or two by now and that the spec authors are rather  
inflexible about this point (and no new arguments have swayed them)?

Having a distinguishing feature at this time would make it possible to  
build tools which failed more gracefully when feed a document from a  
newer spec, as well as simplify the issue of checking conformance for  
a tree of mixed documents.

Suppose an HTML5 conformance checker were fed an HTML6 document. If  
there were a way to distinguish the two based on version, the  
conformance checker could say "This document declares conformance to  
HTML6, but we only know how to check conformance for HTML5" rather  
than generate a bunch of error messages for new elements/attributes.

To be clear, I'm not approaching this solely from the point of view of  
the technical aspects of the specification. I'm approaching it from  
the point of view of wanting to put useful tools in the hands of users  
that they can use today, on their legacy documents, and carry them  
forward to HTML5 (and beyond.)

These tools need to be easy to use, require as little configuration as  
possible (ideally none). Anything else, in my experience, will  
frustrate users, and they'll just abandon the tools and not worry  
about writing conformant documents.

For many people, it is a huge step to go from "works in my browser" to  
using any sort of conformance checker at all. Making the tools harder  
to use in real world situations won't help that cause.

Jim