d) Necessary but not sufficient condition

In T 437/17 the board, in line with several decisions such as T 1472/15 and T 1852/13, held that fulfilling the three criteria of the "essentiality test" as set out in T 331/87 (OJ 1991, 22) was a necessary requirement but not a sufficient one for compliance with Art. 123(2) EPC. The board further underlined that, in any case, this test could not replace the "gold standard" and should not lead to a different result than when applying the "gold standard" directly.