The essential activities of the organization are undertaken by the Commissions. They work in the following fields:
The commissions usually meet once each year. Every centre is encouraged to send a delegate to the commission meetings, invidividual members of OISTAT are most welcome to take part in the commission meetings. The principle of the OISTAT activities is based on mutual in vitations, extended by the centers. They extend invitations to a commission to meet in their country. The centres bear the cost of accommodation and food according as defined in the statutes. The organization of such meetings is an essential factor for an OISTAT membership. Every four years, the commission elects a chair whose job it is to organize the meetings as well as the activities between meetings, propose themes and coordinates the projects.