Opening of national research programmes has gained importance as mean for increasing international collaborations and for improving quality and efficiency of scientific research both at the national, European and international level. The concept of opening refers to the fact that actors not belonging to the national research space can participate in research funding programmes. 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, agreements for international collaborations (with or without complementary funding). This underlines the importance for descriptors and indicators, which could provide evidences of different patterns of opening and contrasting perspectives on policy motivations and goals behind opening decisions. The paper aims at presenting the descriptors and indicators used for exploring opening patterns and logics which characterize main project funding instruments in three countries (CH, FR, IT) on the base of data collected in the within of the JOREP project trying to identify national research policy perspectives behind the decision of opening large national research programmes. Evidence emerging for the three countries surveyed are presented and discussed.