Dear,
Some extra XMP extension schemas (and so namespaces and tags) are defined in the standard ISO 19005-1:2005 about PDF/A:
https://www.iso.org/standard/38920.html
https://portal.tcu.gov.br/lumis/portal/file/fileDownload.jsp?fileId=8A8182A24F0A728E014F0AF414232619
See § 6.7.8 p. 16-19.
https://www.pdfa.org/wp-content/uploads/2011/08/tn0001_pdfa-1_and_namespaces_2008-03-182.pdf (first corrigendum of the standard)
https://www.iso.org/standard/60603.html (second corrigendum, not available for free).
See also:
https://www.pdfa.org/wp-content/uploads/2011/08/tn0008_predefined_xmp_properties_in_pdfa-1_2008-03-20.pdf - See especially § 1.1 PDF/A Identification Schema and § 3 Auxiliary Schemas
https://www.pdfa.org/wp-content/uploads/2011/09/tn0009_xmp_extension_schemas_in_pdfa-1_2008-03-20.pdf - See § 4 PDF/A-1 Extension Schema Container Schema
Maybe these elements (at least the most used of them, e.g. about PDF/A compliance information) are worth to be taken into account by ExifTool and added to:
https://exiftool.org/TagNames/XMP.html
Regards,
Jeff
Might you have any samples to share containing the extended XMP?
- J