Sometimes is hardly to establish the boundary between sympathizer of illegal communist movement and “party member” - called in this research “illegalist”. There were many sympathizers who worked as hard as a real party member. In the same time, there were party members who joined sporadically to the party’s activities.
          The boundary between a member of a communist party and a party’s leader is very fragile also. Almost all the subjects who assumed the illegalist status they held one position or another in communist party hierarchy. Some played a role in the upper levels of Party hierarchy, as Central Comitee of Communist Party. Others – at the lower levels of party leadership.
          The concept of “party leader in underground times” could be used in a limited sense – as a member of a central leading structures; and also it could be understand in a large sense, as a member of local party leading structures and, also, as a member in the leading structures of followers organizations.
          If we focus on the interval between 1921 and 1944 and we apply the limited sense of the definition of an “illegalist”, just 300 of persons could be considered “party leaders in underground time”. In our opinion, for these is better to use the term “activists” or “professional revolutionists”, as it was used by V.I. Lenin. In this research, we define “activist” as a party member who completely join the communist party and who understands his/her assignment as a full time job.
          Realistically, in our opinion “illegalist” should mean a person who conducted his/her life according to rules of behavior requested by communist party. As we’ll explain in others parts of this site, the criteria used by RCP after gaining the power for establish the underground internship was a completely artificial one.