Editing Solid modeling (section)

=== Primitive instancing===
This scheme is based on notion of families of object, each member of a family distinguishable from the other by a few parameters. Each object family is called a ''generic primitive'', and individual objects within a family are called ''primitive instances''. For example, a family of bolts is a generic primitive, and a single bolt specified by a particular set of parameters is a primitive instance. The distinguishing characteristic of pure parameterized instancing schemes is the lack of means for combining instances to create new structures which represent new and more complex objects. The other main drawback of this scheme is the difficulty of writing [[algorithm]]s for computing properties of represented solids. A considerable amount of family-specific information must be built into the algorithms and therefore each generic primitive must be treated as a special case, allowing no uniform overall treatment.