A plurality of independent claims in different categories (see F-IV, 3.1) may constitute a group of inventions so linked as to form a single general inventive concept as defined in Rule 44(2).
However, it is essential that a single general inventive concept link the claims in the various categories. The presence in each claim of expressions such as "specially adapted" or "specifically designed" does not necessarily imply that a single general inventive concept is present.
Source: http://www.epo.org/law-practice/legal-texts/html/guidelines/e/f_v_3_2_2.htm
Date retrieved: 17 May 2021