Limitations related to the subject-matter
The EPO is not required to perform an international search if the application relates to subject-matter which is not regarded as an invention or susceptible of industrial application or which is excluded from patentability under the provisions of the EPC. Here, the criteria applied for the decision not to perform an international search are the same as for the European procedure. This means that the discretion of an ISA not to search subject-matter set forth in Rule 39.1 PCT is used by the EPO as ISA only to the extent that such subject-matter is not searched under the provisions of the EPC.
WIPO PCT Guide 7.013
Source: http://www.epo.org/applying/international/guide-for-applicants/html/e/ga_c3_3_4.html
Date retrieved: 17 May 2021