ACIS, Parasolid, SMLib, and Designbase - commercial geometry kernel providers whose strategy is to solve problems by becoming the industry standard. Unfortunately, all are excellent products with equally wide distribution. Effective but often expensive and not always the best tools. Ineffective, since no single core product has yet emerged as the standard for 3-D modeling.
Wide use is encouraged.
Diverse development is encouraged. There are no restrictions. Neither copyright nor copyleft restrictions. No contribution of effort or technology is required from the members, although it is encouraged.