<div dir="ltr">Markus, Marco, and whoever else is tracking...<div><br></div><div>I'm not automatically sure it's true that "most PIDs are URIs", but it might depend on whether you mean the specific formation scheme as opposed to the total number of identifiers created and/or resolvable. Technically (and implementationally), once a URL is used as a PID it must be assumed that at some point it will no longer "dereference itself". URLs can change; identifiers that change (rather than, say, accumulating aliases) fail the 'P' test for PIDs.</div><div><br></div><div>Yes, I would very much like to see a collection of use cases, even somewhat vague ones. I can think of many potential uses for PIDs, but I don't have an instinct for how many of them might be useful/actionable/interesting in the IVOA environment.</div><div><br></div><div>Here are some potentially interesting links on the generalized PID end of things:</div><div><ul><li>The PID Forum (blog format). I haven't done a lot of digging around in it myself, but I've followed a number of references to articles posted here: <a href="https://pidforum.org/">https://pidforum.org/</a></li><li>There is a PID Interest Group in the Research Data Alliance, though they haven't produced much in the way of public artefacts. More interesting is the RDA <a href="https://www.rd-alliance.org/recommendations-and-outputs/catalogue">Outputs & Recommendations Catalogue</a>, where I see more than a couple documents that look to be worth reading.<br></li><li>If you want a broader sample of what's going on with PIDs in other disciplines, you can peruse the schedule for the last PIDapalooza event here: <a href="https://www.pidapalooza.org/">https://www.pidapalooza.org/</a></li></ul>Regards,</div><div><br clear="all"><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr">-Anne.</div></div></div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Nov 9, 2021 at 4:50 AM Markus Demleitner <<a href="mailto:msdemlei@ari.uni-heidelberg.de">msdemlei@ari.uni-heidelberg.de</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hi Anne,<br>
<br>
On Mon, Nov 08, 2021 at 04:22:36PM -0500, Anne Catherine Raugh wrote:<br>
> The next question I would have is "How is 'PID' defined?". For example,<br>
> every PDS product has a unique URI created by PDS, and if you type it into<br>
> a PDS search you can, theoretically at least, get straight to the<br>
> associated product. But although our archive will persist for generations,<br>
> I still wouldn't consider our PDS product URIs to be PIDs. There's a level<br>
> of broad acceptance and independence from the individual publisher or<br>
> curator that things I think of as PIDs have, that the PDS URIs do not.<br>
<br>
First off, I don't think we can fit a definition I'd be happy with<br>
into the very terse definitions we have in the UCD list (these should<br>
normally work in definition-generating machinery, cf. the Explanation<br>
column on<br>
<<a href="http://dc.g-vo.org/ucds/ui/ui/form?__nevow_form__=genForm&description=Error&_FORMAT=HTML&submit=Go" rel="noreferrer" target="_blank">http://dc.g-vo.org/ucds/ui/ui/form?__nevow_form__=genForm&description=Error&_FORMAT=HTML&submit=Go</a><br>
for combined UCDs). Hence, I'd say Yan's "Persistent Identifier" is<br>
about as good as it gets for that purpose.<br>
<br>
But for future reference when someone is in doubt, I agree it would<br>
be good to attempt a delineation of what we do and don't mean be PID<br>
in the RFM. <br>
<br>
Now, I can't say I'm happy with that the Wikipedia currently says:<br>
<br>
A persistent identifier (PI or PID) is a long-lasting reference to<br>
a document, file, web page, or other object.<br>
<br>
Mainly, I don't think the "long-lasting" is the decisive criterion<br>
here, as I've personally defined URIs in 1996 that still resolve to<br>
conceptually the same thing (where I'm dodging the nasty question of<br>
identity: How much can change in a document before it changes its<br>
identity?). I'd say that's long-lasting all right, but these URIs<br>
certainly shouldn't be counted as PIDs.<br>
<br>
I'd propose something like "PIDs in general are vendor-neutral<br>
identifiers with a defined curation scheme designed to cope with<br>
reasonable changes in resolution of other identifiers (e.g., DOIs for<br>
documents with different or multiple http URIs) or changes in other<br>
identifying characteristics (e.g., an ORCID for authors with names<br>
evolving due to transliteration or marriage) and a well-defined<br>
resolution mechanism. Note that normal IVOIDs are *not* persistent<br>
identifiers, as they will change when resources migrate between<br>
authorities." for our rationale.<br>
<br>
I'm sure in the context of, e.g., the RDA, much better definitions<br>
have been come up with, which perhaps even address some of the less<br>
hairy problems of "identity". If someone has a quick reference: I'd<br>
be curious, too.<br>
<br>
-- Markus<br>
</blockquote></div>