Apple has posted schematics for the iPhone 5S and iPhone 5C. This is designed for case designers. Anyone putting together a case for the iPhone 5S or iPhone 5C needs to know the exact dimensions of the handsets in order to make something that fits it correctly.
It means nothing to the rest of us, unless you are that interested in learning the exact dimensions of your iOS devices. You know … for fun, or something. Still, it’s cool to see Apple make this information available. That said, it can only benefit the Cupertino company, because it means people are spending money on its products and on accessories for its products.