The opening of national research programs has gained importance as a means for increasing international collaboration and for improving the quality and efficiency of scientific research at the national, European, and international levels. The concept of opening refers to the fact that actors who do not belong to a national research space can participate in research funding programs. This complex and multidimensional phenomenon can be operationalized through different measures: the participation of foreign partners in domestic research activities with or without funding, the portability of grants when moving abroad, and agreements for international collaboration (with or without complementary funding). This underlines the importance of having descriptors and indicators, which could provide evidence of different patterns of opening and contrasting perspectives on policy motivations and goals behind opening decisions. The article presents the descriptors and indicators used for exploring opening patterns and logics, which characterize the main project funding instruments in three countries (Switzerland, France, and Italy) on the basis of data collected within the JOREP1 project. Preliminary evidence emerging from the three countries surveyed are presented and discussed.