Re: new itemscope or not?

This thread is playing out some of the thoughts I have been having around
the issue of representing identifiers for a while.  It is a classic ³I would
not of started from here² problem.

In the ideal world everything would have it¹s own identifier that everyone
would recognise as being unique and in the Schema/RDF world it would be a
resolvable http URI.

However, we have been creating identifiers for things, people, etc, for
decades and continue to do so.  Often these identifiers can be considered as
things in their own right.  For example, an ISBN has properties such as
issuing authority, organisation it was issued to, issue date, book, and of
course the string of characters which is the number itself.  This is a
pattern that is repeatable in a lesser or greater degree for many
identifiers from EAN¹s to social security numbers.

One approach to associating these numbers is the one taken with Book.
Predefine what identifiers can be associated with a thing and provide an
attribute for it ­ Book:isbn.  The problem with this approach occurs when
the addition of more of these identifiers becomes appropriate, as we are
seeing in this conversation about Person ­ do we add attributes for ISNI,
VIAF, ORCID, Social Security Number, etc?

The other approach would be to implement an Identifier class enabling the
description and associated attributes of identifiers from any scheme, plus
having the ability to associate many different identifiers.  As Ed says,
this may be applicable for most classes of thing, so why not add an
Identifier property to the Thing class.

Essentially it is choice between constrained simplicity (Book:isbn) which
prevents you from adding identifiers not thought of at schema definition
time or; flexibility which introduces a complexity of indirection that many
would not expect.

~Richard

On 07/09/2012 20:19, "Dawson, Laura" <Laura.Dawson@bowker.com> wrote:

> So many identifiers are not URLs. They can be related to URLs (as DOIs) but
> they are not URLs themselves.
> 
> I would be reluctant to have VIAF be "the" person identifier.
> 
> On Sep 7, 2012, at 3:15 PM, Jeni Tennison <jeni@jenitennison.com> wrote:
> 
>> 
>> On 7 Sep 2012, at 20:03, Ed Summers wrote:
>>> It would be interesting to know if the HTML spec allowed multiple
>>> identifiers, similar to how other HTML attributes work:
>> 
>> 
>> "The itemid attribute, if specified, must have a value that is a valid URL
>> potentially surrounded by spaces."
>> 
>> http://www.w3.org/TR/microdata/#attr-itemid
>> 
>> So that would be 'no', not according to spec.
>> 
>> I've often wondered whether the schema.org 'url' property is meant to be
>> synonymous with itemid. I'm not sure what happens in schema.org interpreters
>> when you specify one/other/both/multiple urls...
>> 
>> Jeni