Caffeine in a pill is it the outside that's coded or the inside beneath or the whole pill?...im?

You are so confused that you can't even type a coherent question. A pill is not "coded", it's "coated". A layer of material is applied to the outside like a coat of paint.

So a pill might have the active ingredient in the coating, or inside the coating, or the whole pill might be a homogeneous product.

Next comes a question: "What are we trying to achieve with this pill?" I hope it's obvious that whatever is on the outside of the pill gets absorbed into the system first. If the active ingredient were in the coating, there would be no reason to have anything else in the pill, so that is highly improbable. If there is no other ingredient in the pill then there is no reason to play games with layers.

A pill consists of an active ingredient mixed with a binder, something that only holds the shape of the pill. Caffeine is not associated with anything else, so it is made in an uncoated pill.