[NTG-context] XMP metadata schema yields invalid PDF/A

Karl Pettersson karl.pettersson at klpn.se
Fri Feb 4 23:11:33 CET 2022


On Fri, Feb 04, 2022 at 10:25:27PM +0100, Hans Hagen via ntg-context wrote:
> On 2/4/2022 7:29 PM, Karl Pettersson via ntg-context wrote:
> > Hi
> > 
> > PDF/A files generated using ConTeXt fail validation with veraPDF, and
> > the reason seems to be that the dc:description metadata is defined with
> > the wrong type in the embedded XMP extension schema.
> > 
> > https://tex.stackexchange.com/questions/632380/generate-pdf-a-with-context
> > 
> > https://github.com/veraPDF/veraPDF-library/issues/1224
> > 
> > I can reproduce the problem using TeX Live 2021 (MkIV 2021.03.05). The
> > definition seems to be controlled by this code.
> > 
> > https://source.contextgarden.net/tex/context/base/mkiv/lpdf-pua.xml?search=rdf#l81
> so "dc:description" is not permitted? it is mentioned in
> 
> https://www.dublincore.org/specifications/dublin-core/dcmi-terms/#http://purl.org/dc/elements/1.1/description
> 
> (btw it never failed before)

The description element is permitted, but the problem seems to be that
its valueType is defined as Text in the embedded schema, while the
metadata element in the PDF has an embedded <rdf:Alt><rdf:li
xml:lang="x-default"> structure.

https://github.com/veraPDF/veraPDF-library/issues/1224#issuecomment-1029932963

(I suppose the reference to "title" in the issue comment should be "description".)

Validating with veraPDF <1.20 does not raise the error. The validation
seems to have changed for redefined types in that version.

https://github.com/veraPDF/veraPDF-library/blob/integration/RELEASENOTES.md#validation

> 
> Hans
> 
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-- 
Karl Pettersson
Uppsala, Sweden

https://static-dust.klpn.se/


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