The API cross references give an immediate access to relevant interfaces and classes.
A point is a location with two coordinates.
A rectangle is an area defined by it's top left corner, its width and its height.
A dimension is a rectangle with an entry point. Its upper left corner and its virtual exit point coordinates are given according to the entry point.
A size is a dimension with an explicit exit point.
A position is a point with respect to some origin which is either the father or the brother.
A transformer translate some coordinates according to its origin.
[PENDING : links to the developer manual]