On second thought, the one accepting shouldn't care should it? It is just getting what it thinks is a normal form submission, and if the encoding is done the same as an HTML form, it should not have any problem with the binary data, right?
submit with binary attachments
submit with binary attachments
Yep, that's before Vortex could accept full binary data in POSTs as well (was added same time as support in <submit>). You could try to <strfmt "%U"> the PDF before passing it to <submit>, and using <readvars> to decode it on the other end. However, that's really going to bloat the data, as it's double-URL-encoded.