It is established case law that a specific disclosure destroys the novelty of a generic feature in a claim but that a generic disclosure does not destroy the novelty of a specific feature (see T 651/91, T 776/07, T 1174/05, T 6/04, T 776/07). A generic disclosure does not normally deprive a claimed specific embodiment of novelty (T 1786/09, see also Guidelines G‑VI, 5 – November 2015 version).
In T 651/91 the board pointed out that a generic disclosure did not normally deprive any specific example falling within that disclosure of novelty. A disclosure could be generic even where it only left open the choice between two alternatives. In T 508/91 the board held that, on the other hand, the prior disclosure of the subset "vegetables" deprived the wider set "fruits and plants" of novelty (see also T 1204/00).