Official and Complementary Publications Explained
Below is a diagram that represents the Official Portfolio and the wider complementary portfolio:

The Official Portfolio includes:
The nature of the OGC core products is such that they need to be interpreted and adapted for use. As a result of feedback from the marketplace, OGC-required products include all Core products and a restricted set of derived products. These derived products include introductions to the framework(s), specific pocketbooks covering key elements of the core framework and study guides in support of the emerging qualifications.
Listings of individuals and organisations that hold active OPSI licenses, whose material is incorporated within the wider complementary portfolio, can be found on OPSI's licensees list.
Discover more about OGC's Best Practice Portfolio and complementary products (pdf - 466KB).