Here’s an example showing blank nodes being used to declare the place of birth is unknown in Wikidata:
https://w.wiki/6$y
In the UI, it is rendered like this:
[cid:image001.png@01D550F5.6E2E10E0]
Jeff
From: Daniel Hernandez <daniel@degu.cl>
Date: Monday, August 12, 2019 at 9:42 AM
To: "semantic-web@w3.org" <semantic-web@w3.org>
Subject: [External] Re: The Joy of NULLs (not)
Resent-From: <semantic-web@w3.org>
Resent-Date: Monday, August 12, 2019 at 9:37 AM
As Enrico pointed, blank nodes can be used to represent unknown values.
An example of this use is Wikidata. I don't know another example.
--
Daniel
On Mon, 12 Aug 2019 07:36:41 +0000
Franconi Enrico <franconi@inf.unibz.it> wrote:
> Mike, this could easily happen in an RDF world if you register a
> vanity licence plate with anything starting with "_". Indeed, bnodes
> would be the right way to represent unknown but existing plates. --e.
>
> Il giorno 11 ago 2019, alle ore 23:10, Michael F Uschold
> <uschold@gmail.com<mailto:uschold@gmail.com>> ha scritto:
>
>> This is hilarious. It could never happen in an RDF world! No value,
>> no triple.
>>
>> He tried to prank the DMV. Then his vanity license plate backfired
>> big time.
>> https://mashable.com/article/dmv-vanity-license-plate-def-con-backfire/<https://mashable.com/article/dmv-vanity-license-plate-def-con-backfire/><http://flip.it/NIk7FD<http://flip.it/NIk7FD>>
