本节介绍用于创建表机构的GRIP语句。此外包括了声明，以确定关联的底的偏移的体。
片体创建操作分为以下几类：
在这一节介绍的的建模方面：
Feature is a all-encompassing term that refers to all solids, bodies, and primitives.
A body is a collection of faces and edges. This includes both solid bodies and sheet bodies.
A solid body is a collection of faces and edges that "close up" to enclose a volume
A sheet is a body with a zero thickness, similar to a surface, made up of a collection of faces and edges that do not "close up" to enclose a volume. Each sheet has an underlying surface type, such as a surface of revolution, cylinder, B-surface, etc., that defines its shape.
A face is a region on the outside of a body, separated from other faces by strings of edges.
The statements in this chapter create sheet bodies based upon the type of underlying surface desired. For statements which create B-surface type sheets, if the resulting body is closed in both U and V directions, it is a solid body. If the resulting body is closed in one direction and the other direction has planar ends, then it also creates a solid body.
If a Modeling Application statement allows you to specify a distance or angle tolerance value and you do not provide one, the default is the value set in the Unigraphics option for Preferences—>Modeling. You can read and set these tolerance values using the GPAs &DISTOL and &ANGTOL.
If a Modeling Application statement performs an approximation and that statement does not allow the minor word TOLER, the system uses the tolerance value set in Unigraphics.