When lack of unity is established, the sequence of the claimed (groups of) inventions will normally start with the invention first mentioned in the claims ("first invention"); see also B‑VII, 1.1 and B-VII, 2.3. In other words, as a general rule the division of subject-matter follows the order of appearance of the different inventions in the claims. The content of the dependent claims will be taken into account when determining the first invention. Trivial claims relating exclusively to features that seem unimportant in the light of the invention or that are generally known in the technical field of the invention are disregarded (see B‑III, 3.8 for the search phase).
However, if the filed claims do not fulfil the requirements of Rule 43(4), i.e. if the dependency of the claims is not correct, the claims will be re-ordered accordingly before assessing the fulfilment of the requirements of unity.
No objection on account of lack of unity is justified in respect of a dependent claim and the claim on which it depends (see F‑V, 2.1).
If, however, the independent claim appears not to be patentable, then the question whether there is still an inventive link between all the claims dependent on that claim needs to be carefully considered (see F‑V, 4.2).
For a definition of a dependent claim, see F-IV, 3.4, and F-IV, 3.8.