OEC Volumes (1991): Scientology organizational theory divides the "cycle of production" into seven primary areas of activity — each of which is represented by a division within a Scientology organization. Hubbard wrote Policy Letters to guide each of those divisions and in the OEC Volumes these have been grouped into seven separate volumes representing each division: personnel, promotion, fiscal, production, quality, distribution and leadership. Staff of a particular division turn to their corresponding volume for the policy that governs their division. The most highly-trained administrators study all seven volumes in the Organization Executive Course available both inside and outside the Church of Scientology.