PCT (Patent Cooperation Treaty) applications are published with an "International Search Report" appendix document. This is done by one of the larger patent offices from the countries in the PCT, and is a preliminary assessment of the patentability of the claims in the application. The searchers try to identify other documents in the patent or open literature that might bear on their novelty or scope.
It would be difficult to pay me sufficiently to do this for a living. I've been involved in many in-house patentability and claim-writing discussions, and they can be agonizingly tedious and frustrating. That's why I've never been able to understand how some pharmaceutical applications are written. They start off with chemical claims whose first generic structure seems to take in the vast reaches of interstellar space. Then the next fifty or sixty claims narrow this down in gratingly tiny steps to oh, about the edge of the Kuiper belt. Then comes a recitation of six hundred and seventy-eight specific names of compounds that are specifically claimed, and on and on.
I have trouble imagining how anyone can go to such pains, and I have trouble imagining why they bother. After all, if you don't enable these claims (patent-speak for "show that you actually made something that fits that description"), they're not worth all that much if it comes down to a fight. And I've seen many claims that couldn't be fully enabled short of putting five hundred people to work on them full-time for about ten years.
For those of you with access to patent images, try the generic structure in US6214850 on for size. It's very concise, as these things go, but rapidly expands like some sort of mutant fungus. For a wordier example, try WO2002042272. This jewel has 139 pages of claims in it, and the number of R-groups that show up in its laughable generic structures goes up into the hundreds.
The whole purpose seems to be to confuse and irritate anyone who tries to read the claims - and to be fair, that's very likely just that the purpose is, since that makes it harder for someone else to figure out what the real subject of these hay-bale-sized applications actually is. But the poor souls at the search agencies are paid to do that, and every so often they lose it. I just came across a search report which starts out with this cri de coeur:
"In these claims, the numerous variables and their voluminous, complex meanings and their seemingly endless permutations, makes it virtually impossible to determine the full scope and complete meaning of the claimed subject matter. . .it is impossible to carry out a meaningful search on same."