The public may oppose a granted European patent on the basis of one or more of the grounds mentioned in Art. 100. The grounds on which the opposition is based may arise for example from circumstances of which the EPO was not aware when the patent was granted (e.g. prior use or a publication which was not contained or not found among the material available to the EPO). Opposition is therefore a means by which any person (but see D-I, 4) may obtain the limitation or revocation of a wrongly granted patent.