I'll have to look back to see if I in fact have added to the fundamental meaning of what others have called "layering." The pad doesn't absolutely have to be an

I'll have to look back to see if I in fact have added to the fundamental meaning of what others have called "layering." The pad doesn't absolutely have to be an OTP, particularly when rolling your own layer, if the pad isn't the only key, and the key can change. Watermarks are extinguished when XORed with any genuinely decent (random-imitating, not frequency-bustable) encryption, true. And you're right, at least one layer should not have a watermark. Order doesn't matter though, there really isn't an order for the layers, they're merged with one another. A not-very-good roll-your-own encryption scheme, if it introduces a very large number of permutations (such as starting pad, key) can be very helpful as a layer even though it would be a huge fail as stand-alone encryption. Mechanisms to increase adjust the size (of all but one layer, anyway) are advisable.