The search division takes into account documents published between the earliest priority date and the filing date of the application under consideration, and these documents are identified as such in the search report (see B‑X, 9.2.4). For identifying these documents when an application has more than one priority date, the oldest date is to be applied. When deciding which documents to select for citing in the search report, the search division refers to these dates and chooses preferably any document published before the date of priority. Thus, for example, where there are two equally relevant documents, one published before the date of priority and the other after that date but before the date of filing, the search division will choose the former (see B‑IV, 3.1, second paragraph).
Source: http://www.epo.org/law-practice/legal-texts/html/guidelines/e/b_vi_5_2.htm
Date retrieved: 17 May 2021