RE: ISSUE-4: Versioning, namespace URIs and MIME types

>> I am proposing two mechanisms, not one.
>> (a)    define different MIME types
>> (b)   *also* allow a root element/attribute which distinguishes  
>> between the types

> In that case, I'd point out that using a new MIME type in addition to  
> a distinctive root element/attribute in the markup doesn't add  
> anything relative to just doing the latter. And it retains some of the  
> downsides I cited. So I still don't think it is a very good solution  
> for ISSUE-4.

Argument for two versioning mechanisms rather than one:

Language components without distinctive root element/attributes
or even namespaces at all can be passed around unchanged, given
sufficient contextual information about which language was
intended. The MIME type supplies that contextual information.
When embedding one document in another, the contextual information
needs to be made explicit. Having both mechanisms adds complexity
but allows both nested content and also uniform content without
any explicit versioning information.

I think the "downsides" can be avoided by making the appropriate
choice, and that the choice is available with appropriate 
processing. I suppose we'll need to go through some use
cases and scenarios to verify that, though. 

Larry
-- 
http://larry.masinter.net