Lack of unity may be directly evident a priori, i.e. before considering the claims in relation to the prior art, or may only become apparent a posteriori, i.e. after taking the prior art into consideration - e.g. a document within the state of the art as defined in Art. 54(2) shows that there is lack of novelty or inventive step in an independent claim, thus leaving two or more dependent claims without a common inventive concept (see III, 7.8).