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.
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.