An object from the class SpatialDataSet contains other objects from GeographicObject. Because SpatialDataSet is a subclass of GeographicObject, recursion is possible. That is, a spatial data set can be defined in terms of other spatial data sets.
A spatial data set is distinguished from a geographic composite because of semantics, and possibly externally available services. A spatial data set typically pertains to a collection of geographic objects which define some survey project or which represent a complete description of some general region of space. Cataloguing or high level repository descriptions (outside the scope of SAIF) may reference available spatial data sets.