On Sat, Feb 5, 2022 at 9:48 AM Karl Pettersson <karl.pettersson@klpn.se> wrote:

Attach metadata xml for the non-validating and validating example
(extraced with `pdfinfo -meta | xmllint format -`) in the
Github issue.

Here is a reference to the description element. Note that only
description seems to be redefined, not title.


it's not redefined -- it's dropped. And this is ok.
You can also check with 
  <dc:description>FOO</dc:description>
      <dc:title>
        <rdf:Alt>
          <rdf:li xml:lang="x-default">TITLE</rdf:li>
        </rdf:Alt>
      </dc:title>
and again it's valid.
But 
https://www.iso.org/obp/ui/#iso:std:iso:19005:-1:ed-1:v2:cor:1:v1:en
and 
https://www.iso.org/obp/ui/#iso:std:iso:19005:-1:ed-1:v2:cor:2:v1:en:tab:1
suggest that dc:description and dc:title are of the same type,
which is coherent with 
XMPSpecificationPart1.pdf
as in
https://github.com/adobe/XMP-Toolkit-SDK/tree/main/docs

I.e. these are correct   --  but Subject must agree with dc:description
  <dc:description>
        <rdf:Alt>
          <rdf:li xml:lang="x-default"/>
        </rdf:Alt>
      </dc:description>
      <dc:title>
        <rdf:Alt>
          <rdf:li xml:lang="x-default">TITLE</rdf:li>
        </rdf:Alt>
      </dc:title>
 
At least, this is what I understand.

--
luigi