This is a sample data model. It contains the IVOA UML Profile and imports the IVOA_Profile data model with primitive types. It has some sample relationships etc to be used in documentation etc. major axis of error ellipse Position angle of error ellipse in coordinate system of position. The longitude part of this position in units of degrees. The latitude part of this position in units of degrees. Error of a position on the sky. Generic base class for all astronomical objects.