Re: Microdata: itemid attribute (feedback)

Here are a couple of cases for itemid that we are working on and absolutely
need itemid for.

1) Aggregating data from different sources about an entity: We are working
with a small number of agencies (govt. and non-govt) that publish
environmental and census related data about different locations, towns,
professions, etc. We are depending on itemid for uniquely identifying the
various entities (locations, professions, etc.) so that we can aggregate the
data properly.

2) In the context of search: Google & Yahoo both use structured data in
documents to decorate search result snippets. It would be great to use this
data in other search contexts. E.g., if Yelp reviews Acme's plumbing, in
addition to using the Yelp review data for the yelp search result, if we
could reliably associate that data with Acme's website, the structured data
becomes much more useful.

Yes, we could, on a case by case basis, invent new attributes that are
equivalent to itemid. But given how frequently the need for it crops up, we
would very much like to have one as part of the microdata spec.

guha