T 0194/84 (Cellulose fibres) du 22.09.1988

The test for additional subject-matter corresponds to the test for novelty only insofar as both require assessment of whether or not information is directly and unambiguously derivable from that previously presented, in the originally filed application or in a prior document respectively. An amendment is not allowable if the resulting change in content of the application, in other words the subject-matter generated by the amendment, is novel when compared with the content of the original application. Therefore what is to be tested is the change in content, i.e. the amended content minus the original content. Only then is the test applicable also to amendment by generalisation or omission of a feature (cf. point 2.4 of the Reasons).