[dev-context] attachments with PDF/A-3

Dear list, I have generated a PDF/A-3 compilant document, but as I add attachments the validation from veraPDF warns about errors. There are five issues, which I can document here. Sorry, but I’m afraid I cannot provide patches. Can we discuss these issues now, or is it better to wait until TeX Live 2019 has been released? Many thanks for your help, Pablo -- http://www.ousia.tk