Bookcase doors may have hundreds of pounds of weight when loaded.
1/16" to 1/8" deflection can cause door alignment failure, scraping and bookcase damage.
Bookcases are fitted into a custom fabricated steel frame which is welded to a steel post, resulting in about 1/64" deflection when fully loaded.
Bookcase doors are fitted with an electromagnetic lock. The magnetic latch is released by pressing a hidden button and/or a remote key-chain button.