# 8.9.3.21 IfcCompositeCurveOnSurface

## 8.9.3.21.1 Semantic definition

The IfcCompositeCurveOnSurface is a collection of segments, based on p-curves. i.e. a curve which lies on the basis of a surface and is defined in the parameter space of that surface. The p-curve segment is a special type of a composite curve segment and shall only be used to bound a surface.

There shall be at least positional continuity between adjacent segments. The parameterization of the composite curve is obtained from the accumulation of the parametric ranges of the segments. The first segment is parameterized from 0 to l~1~, and, for i ≥ 2, the i^th^ segment is parameterized from

Entity adapted from composite_curve_on_surface defined in ISO 10303-42.

## 8.9.3.21.5 Formal representation

ENTITY IfcCompositeCurveOnSurface
SUPERTYPE OF (ONEOF
(IfcBoundaryCurve))
SUBTYPE OF (IfcCompositeCurve);
DERIVE
BasisSurface : SET [0:1] OF IfcSurface := IfcGetBasisSurface(SELF);
WHERE
SameSurface : SIZEOF(BasisSurface) > 0;
END_ENTITY;