intervened during the appeal. Observations by third parties under Article 115 EPC Independently from the possibility to intervene in opposition proceedings (and then to become party to the proceedings), anyone may also file observations under . After publication of a European patent application, and a fortiori after grant of a European patent, anyone may file observations regarding the patentability of the invention which is the subject of the application (during examination proceedings) or patent (during opposition proceedings). In contrast to an intervener however, a person filing observations during opposition proceedings does not become party to the proceedings. This notably means that such person does not acquire the "bundle of procedural rights" created "in respect of the opponent", such as the right to be heard before any decision is taken. Observations by third parties, which must be filed in writing, may be filed by post or online. According to Board of Appeal 3.3.08, the observations have to be signed "in order to allow an identification of the third party" and, unless "adopted by a party to the proceedings as its own" or by the competent organ of the EPO of its own motion, "anonymous third party observations are to be disregarded altogether." Statistics, costs and duration Overall, about 5.5-6% of the European patents granted by the European Patent Office are opposed. Of those, over the course of 1980–2005, about 1/3 were revoked, 1/3 were maintained in an amended form, which generally means "reduced in scope", and 1/3 were maintained as granted, that is, the opposition was rejected. The same figures were cited in 2013. The opposition rate (i.e. the number of oppositions filed per 100 granted patents) before the EPO is consistently higher in the closest available proxy for the pharmaceutical sector than it is in organic chemistry and in all sectors (overall EPO average). The success rate depends however on the technical area (i.e., on the IPC classes). The main reasons for revocation of a patent in opposition are a lack of inventive step (43%), a lack of novelty (22%) and an extension beyond the content of the application as filed (11%). Filing an opposition before the EPO is reportedly relatively affordable, "as the cost varies between €6000 and €50,000 (including patent lawyers’ fees)" (as of 2009). In contrast, the costs for litigating a European patent can be much higher ("For example, in Germany the total litigation costs can be