Reasons of economy dictate that the examiner use his judgement to end his search when the probability of discovering further relevant prior art becomes very low in relation to the effort needed. The search may also be stopped when documents have been found clearly demonstrating lack of novelty in the entire subject-matter of the claimed invention and its elaborations in the description, apart from features which are trivial or common general knowledge in the field under examination, application of which features would not involve inventive step. The search for conflicting applications should, however, always be completed to the extent that these are present in the available documentation.