1. General remarks 

The requirement of unity of invention has a regulatory function and is intended to promote an efficient procedure up to grant (T 110/82 and F‑V, 6). It would be unfair to treat applications as meeting this requirement where, because of their diverse content, they cost much more than average to process, especially in terms of search, since some of this extra cost would have to be covered by fees paid for other applications. Another aspect is that an application's content should be readily understandable, which will not always be the case where its subject-matter is very diverse.

On the other hand, the general purpose of dealing with linked substantive issues in a single procedure would not be achieved if the provisions on unity of invention were applied too strictly, and so interconnected subject-matter must not be split up needlessly (see F‑V).