AFAIK one can embed arbitrary RDF into PDFs, and then one wouldn't need an extra field https://pdfa.org/wp-content/until2016_uploads/2011/08/pdfa_m...
AFAIK one can embed arbitrary RDF into PDFs, and then one wouldn't need an extra field https://pdfa.org/wp-content/until2016_uploads/2011/08/pdfa_m...