The user may define subclasses of this class.
If time is specified, timeUnits must also be specified.
Coordinate accuracy is expressed as a percentile, associated with a horizontal value, a vertical value and a time value. For example, 95% of the points are within 10 m horizontally and 5 m vertically. (The units for horizontal and vertical are given in the spatialReferencing attribute (under SpatialObject).