If you export a document to PDF, the general options in the PDF export dialog shows a checkbox with PDF/A compatibility and secondary options for PDF/A-2b and PDF/A-1b.
These options are not explained in the help files. There is only 'Archive PDF/A-1a (ISO 19005-1)' mentioned.
See https://help.libreoffice.org/latest/en-US/text/shared/01/ref_pdf_export.html from today.
"Archive PDF/A-1a (ISO 19005-1)
Converts to the PDF/A-1a format. This is defined as an electronic document file format for long term preservation. All fonts that were used in the source document will be embedded into the generated PDF file. PDF tags will be written."
Whiteboard said "QA:needsComment" but we cannot say more, so I remove it.