Many Smartphone browsers will not display a PDF document. A PDF
(Portable Document Format) is designed to always display and print
properly, so print materials in the archive are saved in that
format. Phones that don't handle PDF's will just show a blank
screen, with a link to a JPEG (picture) Version of the item. Since
pictures are resized to the size and shape of the screen that they're
on, they may look weird, but will be readable at least.