is followed by the Boards of Appeal of the EPO, is that an invention is patentable if it provides a new and non-obvious technical solution to a technical problem. Referrals to the Enlarged Board of Appeal are said to be rare, happening only with the most complex questions. The patentability of software has provoked fierce debate in Europe over the recent years, especially in relation to the proposed European Union (EU) directive on the patentability of computer-implemented inventions. The directive was rejected in 2005 by the European Parliament, a decision that was welcomed by those on both sides of the debate, by those supporting the patentability of software in Europe as well as those opposing it. Questions Four questions have been referred by the President of the EPO to the Enlarged Board of Appeal. The four questions have been chosen to look at four different aspects of patentability in the field of computer programs. Question 1: Claim category A divergence between decisions T 1173/97, making no distinction between categories of claims, especially between computer-implemented claims and computer program claims, and T 424/03, making a distinction between these two categories, is cited as justifying this question. Question 2: Claim as a whole A divergence between decisions T 1173/97 and T 258/03 is cited as justifying this question. Under T 1173/97, computer programs are methods, and in order to have a technical character computer programs must demonstrate a further technical effect (which goes beyond the "normal" physical interactions between program (software) and computer (hardware)). Under T 258/03, a method acquires a technical character simply by involving technical means. Question 3: Individual features of a claim A divergence between, on the one hand, decisions T 163/85 and T 190/94, according to which a technical effect on a physical entity in the real world is required (to escape the exclusion under Article 52(2)(c) and (3)), and, on the other hand, T 125/01 and T 424/03, according to which the technical effects can be essentially confined to the respective computer programs, is cited as justifying this question. Question 4: The activity of programming A divergence between decisions considering that a programmer's activity, i.e. writing computer programs, falls within the exclusions of Article 52(2)(c) (T 833/91, T 204/93, and T 769/92) and decisions having taken the opposite view (T 1177/97 and T 172/03) is cited as justifying the question. Statements by third parties (Amicus curiae briefs)