title: IPTC metadata automatically added to uploaded images on Facebook
body: <p>Many images uploaded on Facebook contain IPTC/IIM fields which are apparently automatically added during the upload process:</p>
  
  <ul>
  <li><em>Special Instruction</em>, a string beginning with "FBMD" </li>
  <li><em>Original Transmission Reference</em>.</li>
  </ul>
  
  <p>See for example this (personnal) image uploaded on Facebook and decoded using Jeffrey's Exif Viewer:
  <a href="http://exif.regex.info/exif.cgi" rel="noreferrer">http://exif.regex.info/exif.cgi</a> </p>
  
  <p>What is this?</p>