Re: [xml-dev] Multiple instances of an attribute Re: [xml-dev] TowardsXM

[David Carlisle <davidc@nag.co.uk>]

On 10/12/2010 09:46, Stephen Green wrote:
> I was also thinking maybe some xml:xxx features added to XML by the XML WG
> (rather than the XML Schema WG) might expand attribute functionality in a
> way which doesn't require a schema


why is a schema needed? What is the use case for being able to parse 
xml+json (say) with no prior knowledge of what vocabulary of the xml 
file is using, but being able to detect that particular attributes are json?

To give counter example:

an xsl file has many structured attributes (typically xpath rather than 
json but the issues are similar)

select="(1,2,3,4,5)"

for example. That xpath has many similarities to json, involving 
sequences and integer literals. there is no schema type for xpath, an 
xslt processor just has advance knowledge that the select attribute 
contains xpath and parses it accordingly. A generic XML processor 
doesn't know that this is xpath and just treats the entire attribute as 
an opaque string, but that's OK it wouldn't help if it did know it was 
xpath, it wouldn't be able to evaluate it anyway.

So, what are the circumstances that xml:json="[1,2,3,4,5]" would help 
over a particular vocabulary having data-json="[1,2,3,4,5]" ?

David


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