Principle underlying Austria's system of Chambers. All individual employees and employers and legal entities falling within the competence of a given Chamber are de jure members of that Chamber. In the field of industrial relations, this relates to the Federal Chamber of Labour (BAK), the Economic Chamber of Austria (WKÖ) and the Chambers of Agriculture. With respect to the WKÖ, this is of particular importance as regards the collective bargaining system: since on the employers' side almost all collective agreements are signed under the umbrella of the WKÖ, the fact that membership is obligatory is a determining factor in Austria's high collective bargaining coverage. Comparative international studies demonstrate that the tendency on the part of employers to opt voluntarily to join an employers' organization decreases with decreasing size of enterprise, although smaller firms gain more than large companies from the representation of their interests and service functions offered by such organizations To that extent, the institution of obligatory membership of a comprehensive organization like the WKÖ reflects the predominance of small firms in Austria's economic and enterprise-size structure.