The published OCX Schema

A collection of 3D curves making up a closed boundary. FaceBoundaryCurve has the following child elements:

Child	Namespace	Type	Use	Cardinality	Choice	Description
Circle3D	ocx	ocx:Circle3D_T	opt.	[0, 1]	True	A circle in 3D space.
CircumArc3D	ocx	ocx:CircumArc3D_T	opt.	[0, ∞]	True	3D Line/Arc representation. Represents a semi-circle uniquely defined by three points in 3D space given by the start position, intermediate position and the end position..
CircumCircle3D	ocx	ocx:CircumCircle3D_T	opt.	[0, 1]	True	Definition of a circle in 3D space by a circumcircle of 3 points.
CompositeCurve3D	ocx	ocx:CompositeCurve3D_T	opt.	[0, ∞]	True	The concept of a composite curve composed of a collection of Line3D, CircumArc3D and/or NURBS segments. Curves are sorted end to end and have C1 continuity across each segment in the CompositeCurve3D definition.
Ellipse3D	ocx	ocx:Ellipse3D_T	opt.	[0, 1]	True	An ellipse in 3D space.
Line3D	ocx	ocx:Line3D_T	opt.	[0, ∞]	True	A straight line defined by two points.
NURBS3D	ocx	ocx:NURBS3D_T	opt.	[0, ∞]	True	Non-Uniform Rational Spline Base curve definition.
PolyLine3D	ocx	ocx:PolyLine3D_T	opt.	[0, ∞]	True	A list of 3D points defining a sequence of linear segments. Repeat the first position at the end of the last line segment to form a closed contour.

FaceBoundaryCurve has the following attributes:

Attribute	Namespace	Type	Use	Default	Fixed	Description
isUVspace	ocx	xs:attribute	opt.	False		If set to True, the FacBoundaryCurve is defined in the parametric UV space. The Pont3D X and Y correspnds to U and V while the Z coordinate is disregarded. The default is False, i.e. the FaceBoundaryCurve is defined in the 3D space.