8.20.2.1 IfcShell

8.20.2.1.1 Semantic definition

A type comprising different kinds of shell.

NOTE Definition according to ISO/CD 10303-42:1992 This type collects together, for reference when constructing more complex models, the subtypes which have the characteristics of a shell. A shell is a connected object of fixed dimensionality d = 0; 1; or 2, typically used to bound a region. The domain of a shell, if present, includes its bounds and 0 ≤ Ξ < ∞. > * A shell of dimensionality 0 is represented by a graph consisting of a single vertex. The vertex shall not have any associated edges. * A shell of dimensionality 1 is represented by a connected graph of dimensionality 1. * A shell of dimensionality 2 is a topological entity constructed by joining faces along edges. Its domain, if present, is a connected, orientable 2-manifold with boundary, that is, a connected, oriented, finite, non-self-intersecting surface, which may be closed or open.

8.20.2.1.2 Type values

Type
IfcClosedShell
IfcOpenShell

Table 8.20.2.1.A

8.20.2.1.3 Formal representation

TYPE IfcShell = SELECT
	(IfcClosedShell
	,IfcOpenShell);
END_TYPE;

8.20.2.1.4 References

IfcShellBasedSurfaceModel

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