Re: PROPOSAL: Errata text regarding defining a prefix of '_'

Oh, and a slightly related question for implementors.  In RDFa it is 
possible to create a *specific* bnode at any time.  They sort of 
"auto-vivify" when you reference them (e.g., about="_:myNewBnode").  At 
least, I think that is how it works.

There are also *implicit* bnodes that get created all the time when 
certain attributes are present.  The names of these are not important.  
What is important is that they become the implicit subject or object of 
triples in their child nodes. These bnodes are by definition CANNOT be 
explicitly referenced, since you have no idea what the implementation 
will name them.

My question is this:  How do you ensure that your implicit, 
automatically created bnode names never collide with a documents 
explicit, auto-vivified bnode names?  And should we have some sort of a 
test case to ensure this happens?

Shane McCarron wrote:
> Just curious - how does it issue a warning?  As part of the graph?
>
> Ivan Herman wrote:
>> Looks fine to me.
>>
>> (I was unsure on the call and I checked: my implementation already does
>> that and issues a warning in case of reusing '_')
>>
>> Thanks
>>
>> ivan
>>
>> Shane McCarron wrote:
>>  
>>> At the 12 November meeting, the group agreed that the RDFa Syntax
>>> Specification reserves the prefix of '_', but that it could be clearer
>>> about this.  We agreed to put a clarification in the Errata.  I propose
>>> the following text:
>>>
>>> In sections 5.4.5 and 7 the specification indicates that the prefix '_'
>>> is reserved and is used to create / reference blank nodes (bnodes). 
>>> Because this prefix is reserved, authors SHOULD NOT declare a mapping
>>> for the prefix '_' and conforming processors MUST NOT incorporate 
>>> such a
>>> prefix mapping into the 'list of URI mappings' as defined in section 
>>> 5.5.
>>>
>>>
>>>     
>>
>>   
>

-- 
Shane P. McCarron                          Phone: +1 763 786-8160 x120
Managing Director                            Fax: +1 763 786-8180
ApTest Minnesota                            Inet: shane@aptest.com

Received on Saturday, 14 November 2009 18:06:53 UTC