# 8.9.3.68 IfcSurface

ABSTRACT This definition may not be instantiated

## 8.9.3.68.1 Semantic definition

An IfcSurface is a 2-dimensional representation item positioned in 3-dimensional space. 2-dimensional means that each point at the surface can be defined by a 2-dimensional coordinate system, usually by u and v coordinates.

Informal Propositions:

1. A surface has non zero area.
2. A surface is arcwise connected.

## 8.9.3.68.4 Formal representation

ENTITY IfcSurface
ABSTRACT SUPERTYPE OF (ONEOF
(IfcBoundedSurface
,IfcElementarySurface
,IfcSectionedSurface
,IfcSweptSurface))
SUBTYPE OF (IfcGeometricRepresentationItem);
DERIVE
Dim : IfcDimensionCount := 3;
END_ENTITY;