Am Donnerstag, 28. September 2023, 12:07:41 CEST schrieb Max Nikulin:
> More I read about .xmpdata, more it looks similar to an ugly kludge from
> my point of view.

Exporting from orgmode to LaTeX needs a high level approach: don't do 
complicated things, just use the appropriate LaTeX API. 

Unfortunately adding XMP metadata is the largest construction site in the 
LaTeX world: https://tug.org/TUGboat/tb43-3/tb135fischer-xmp.pdf 

The LaTeX Project Team developed a new pdf management, see here: https://
ctan.org/pkg/pdfmanagement-testphase : 

"The new PDF management code offers backend-independent interfaces to central 
PDF dictionaries, tools to create annotations, form Xobjects, to embed files, 
and to handle PDF standards."

The most important command is `\DocumentMetadata{}` and it needs to be placed 
before `\ḑocumentclass{}`

The idea to have a LATEX_PRE_HEADER to insert `\DocumentMetadata{}` is exactly 
what you need right now, if you export from orgmode to current LaTeX. With 
`\DocumentMetadata{}` you can add most of the necessary xmp data -- and I 
write most, because I'm using it on a daily basis, but haven't checked if 
really everything is included yet. 

-- 
Regards,
Alexander