Where a technical feature was clearly disclosed in the original application but its effect was not mentioned or not mentioned fully, yet it can be deduced without difficulty by a person skilled in the art from the application as filed, subsequent clarification of that effect in the description does not contravene Art. 123(2).
Source: http://www.epo.org/law-practice/legal-texts/html/guidelines/e/h_v_2_1.htm
Date retrieved: 17 May 2021