Raul explains exactly how Portable Document Format, or PDF, files work. He explains what sorts of objects they're composed of and how analysts could go about peaking inside, even in the case of corrupted PDFs. He also explains how complicated the PDF file format gets with non-English languages, and how, at that point, NSA simply hasn't developed the tools to search them. "If you were looking for Osama bin Laden, and you had entered every Arabic word known to mankind in every possible encoding and Osama were doing nothing more than using PDF and writing in Arabic, you'd never get a hit. Quite reassuring, isn't it?"