CMS collaboration is one of the largest scientific collaborations in history and currently comprises 241 institutes from 54 countries, with over 5000 active members (physicists, PhD students, engineers, and undergraduates).

The construction of the CMS detector was financed by the participating institutes, including the Flemish particle physics groups. Such large scientific infrastructures, however, can only function successfully if every member also contributes a fair share to the exploitation overhead, both financially and with person power. In return, every member can use common software tools, analyse all of the collected data, and publish scientific results.

Thus, the infrastructure of CMS detector and its collected data is accessible only to its scientific collaboration members.