Here are the classes, structs, unions and interfaces with brief descriptions:

CAbstractLine	An Object class that is the base of the line-like Object's: Segment, Line and Ray
CAngle	An Object representing an angle
CArc	An Object representing an arc
CBogusObject	This is the base class for the so-called BogusObject's
CCircle	An Object representing a circle
CConic	An Object representing a conic
CConicCart	An implementation of Conic to be used when only the cartesian equation of the conic is known
CConicCartesianData	Cartesian Conic Data
CConicPolar	An implementation of Conic to be used when only the cartesian equation of the conic is known
CConicPolarData	This class represents an equation of a conic in the form $\rho(\theta) = \frac{p}{1 - e \cos\theta}$
CCoordinate	Basic class representing a 2D location by its x and y components
CCubic	An Object representing a cubic
CCubicCartesianData	This class represents an equation of a cubic in the form $a_{ijk} x_i x_j x_k = 0$ (in homogeneous coordinates, ),
CCurve	This class represents a curve: something which is composed of points, like a line, a circle, a locus..
CDoubleObject	This Object is a BogusObject containing only a double value
CIntObject	This Object is a BogusObject containing only an int value
CInvalidObject	This Object represents an invalid object
CLine	An Object representing a line
CLineData	Simple class representing a line
CObject	Behaviour of an object after it is calculated
CObjectType	Instances of this class represent a certain Object type
CPoint	An Object representing a point
CRay	An Object representing a ray
CSegment	An Object representing a segment
CStringObject	This Object is a BogusObject containing only a string value
CTransformation	Class representing a transformation
CVector	An Object representing a vector

Kig Python Scripting API Documentation