On 08/12/2018 11:48 AM, Ulrike Fischer wrote: > Am Sun, 12 Aug 2018 11:30:03 +0200 schrieb Hans Hagen: > >> (i don't have these iso standards >> as i'm not going to spend money on iso standards) > > One can see quite a number of rules here: > > https://github.com/veraPDF/veraPDF-validation-profiles/wiki/PDFA-Part-1-rules
I think this is also included in the PDF spec (https://wwwimages2.adobe.com/content/dam/acom/en/devnet/pdf/PDF32000_2008.pdf#page=48): If a PDF file contains binary data, as most do (see 7.2, "Lexical Conventions"), the header line shall be immediately followed by a comment line containing at least four binary characters—that is, characters whosecodes are 128 or greater. This ensures proper behaviour of file transfer applications that inspect data near the beginning of a file to determine whether to treat the file’s contents as text or as binary. Just in case it helps, Pablo -- http://www.ousia.tk