[yjftsjthsd-h]

My thought was that if the publisher is trying to hunt people sharing copies, and they have such a copy, it would be useful to be confident that the metadata you embedded is actually accurate; sure, it's obvious if, say, the IP field is zeroed out, but what if they just changed the last octet to 7, and that results in you spending weeks leaning on an ISP to give you the identity of the wrong person? Granted, that's probably more care than Elsevier is likely to take, but the point is that they're passing data through hostile hands, so it'd be sensible to do something for integrity checking.