It may happen that the search division does not find any documents published before the earliest priority date which prejudice the novelty or the inventive step of the claimed invention. In such cases, the search division cites, whenever possible, in the search report at least that prior art found in the course of search which discloses a solution to the same problem as that underlying the claimed invention (wherein this problem may change depending on the prior art retrieved (G‑VII, 5.2) and wherein the known solution is technically the closest to the claimed solution ("closest prior art"). Such prior art is to be cited as an "A" document in the search report (see B‑X, 9.2.2).
If such a document cannot be found, the search division cites as the closest prior art a document which solves a problem closely related to the problem underlying the claimed invention and wherein the solution is technically most similar to that of the application under search.
Where the search division retrieves documents which are incidentally prejudicial to the novelty of the claimed invention (to be cited as "X") but which do not affect the inventive step thereof after appropriate amendment of the application, and does not retrieve any other documents prejudicing inventive step, it also proceeds as above.
In the case of a European application derived from an international application and being subjected to a supplementary European search after entering the European phase (Art. 153(7) – see B‑II, 4.3), it is possible that the search division does not uncover any further relevant prior-art documents in the search over and above the documents already cited in the international search report by the International Searching Authority. In such cases, it is permissible to have no further relevant documents in the supplementary European search report (see B‑X, 9.1.4).