Joseph Smith, and the church today, claim that the Book of Mormon is a translation of an ancient record that was engraved on gold plates that were held together in some type of ring binder (see image below).
Also in the days before computers the Mormons voracious genealogists that they are created records on all of their members. Guess what they stored them in before the magnetic tape became a storage medium? Easy to update as children were added to the flock-binders.
When Mitt Makes a decision on what child bride will be attached to a Mormon man in good standing these binders are referenced.
This might explain Ann Romney's sour look as she contemplated Romney not being able to keep classified material classified.