“The glyphs and symbols are probably some artifact of a poor conversion process,” said Chris Prom, professor and archivist at the University of Illinois Urbana-Champaign. Specifically, the symbols look like remnants of Multipurpose Internet Mail Extensions, or MIME, a 30-year-old standard for encoding emails. Specifically, the Department of Justice likely extracted the email data, converted it to PDF, then redacted it. Or more simply: emails, sometimes partially decoded, converted to PDF, converted to JPEG, converted to PDF. Craig Ball, a forensic examiner who teaches at the University of Texas at Austin School of Law pointed out that different email clients implement standards in slightly different ways, adding to the difficulty of conversion.