John Levine writes: > Among valid PDFs, do you include PDFs that are coded to prohibit text > extraction? How about PDFs that are just bitmap scans of printed > documents, like the PDF versions of some early RFCs from the 1970s? Use the most conservative (and thus probably the earliest) version of PDF. Later versions are designed mostly to make money for Adobe, and they are scarcely needed for documents that contain only formatted text and diagrams. Using an early version of PDF also guarantees that the document can be opened with (almost?) any version of Acrobat Reader or other software. I still use Acrobat 4.x, and I have it set to generate Acrobat 3.x documents, and I've yet to generate any document that requires a more recent version of the software. If you limit yourself to the text and simple artwork that has sufficed for the printed page for the past few centuries, you don't need anything more recent, and you shouldn't be using anything more recent. Be conservative in what you require, and liberal in what you accept. _______________________________________________ Ietf@xxxxxxxx https://www1.ietf.org/mailman/listinfo/ietf