The parent and divisional applications may not claim the same subject-matter, even in different words (for further information, see G‑IV, 5.4). The difference between the claimed subject-matter of the two applications must be clearly distinguishable. As a general rule, however, one application may claim its own subject-matter in combination with that of the other application. In other words, if the parent and divisional applications claim separate and distinct elements A and B respectively which function in combination, one of the two applications may also include a claim for A plus B.
Source: http://www.epo.org/law-practice/legal-texts/html/guidelines/e/c_ix_1_6.htm
Date retrieved: 17 May 2021