The consistent view in the case law is that for an invention to lack novelty, its subject-matter must be clearly and directly derivable from the prior art (see e.g.
T 465/92, OJ 1996, 32;
T 511/92) and all its features - not just the essential ones - must be known from the prior art (
T 411/98). The disclosure is determined by what knowledge and understanding can and may be expected of the average skilled person in the technical field in question (
T 164/92, OJ 1995, 305, Corr. 387;
T 582/93).