Hi Wolfgang, this comes from a previous message from this mailing list (https://mailman.ntg.nl/pipermail/dev-context/2019/003574.html), which I needed a long while to understand 😅. Would it be possible that the \setupattachment command has a "type" key to specify its MIME type? (Default should be "application/octet-stream" [or so it seems].) This is required to add the value to the /Subtype entry in the /Embeddedfile dictionary (https://www.adobe.com/content/dam/acom/en/devnet/pdf/PDF32000_2008.pdf#named...) This is optional information in PDF-1.7, but required in PDF/A-2. Many thanks for your help, Pablo -- http://www.ousia.tk